Just mention you are trying to lose a few pounds, and you will be inundated with Diet Experts. Some of them may understand the science, and some of them may have lost weight themselves, and sometimes both, but you can probably bet on neither.

"Look, here's what you need to do."

People who can't keep a pound off will be telling you to stay off carbs and eat all meats, and others will be telling you to banish meats and stick to carbs. Or that if you eat all bananas in the morning, you can eat whatever you want the rest of the day. Some people will tell you it's all about how often you eat, and other people will say it's all about eating nothing after 7pm (a sort of elderly Gremlin diet).

"Midnight? I can't even stay up past 8 anymore."

Whatever they tell you, they will insist that this is the only right way, that this is THE weight loss secret. It doesn't matter what else you eat, as long as you get that morning banana. Or you stay off carbs. Or whatever. If you don't want to listen, they'll throw up their hands and encouragingly tell you that you're doomed to failure.

Morning Banana would be a good name for a band.

This advice actually comes less from a certainty that whatever they're suggesting will work, than from a certainty that whatever you're doing won't work. About half of all Americans are trying to lose weight at any given time, so any given person is likely to have tried a bunch of different methods, which apparently don't work, otherwise they wouldn't keep trying. It takes an incredible amount of discipline to actually lose weight and keep it off, and most people have trouble accepting how much work they'd have to put in, so when they fail, they blame the method and move on to a new one.

Like the Taco Bell diet. Reasoning: It tastes terrible, so it must be good for you!

Because it can't be because weight loss is really hard. It must be because they just haven't found the right diet yet. This next one must be the right one! And if you, their poor sap of a friend, are trying one of the methods they've already tried and failed at, you're clearly barking up the wrong tree, and they've got to stop you for your own sake.

"Stay off the court, Rick, you are just wasting your time with cardio."

I'd suggest you not tell anyone when you're trying to lose weight, but it's pretty hard to get anywhere when your friends unknowingly take you out to Cheesecake Factory or have you over for backyard BBQs, so you have to tell someone. If anyone gives you trouble, you can just tell them you're on the Facepunch Diet, where you punch someone in the face every time they give you diet advice, and that you have never burned so many calories in your life.

Another stranger told a mom her baby would claw his face off if she didn't cut his nails.

"I can't let them identify me."

Why does everyone want to tell parents what to do, even people with no kids?

Well, parenting is pretty much the most important responsibility most people will ever have -- you have an entire person's life in your hands. So, many parents, especially first-timers, tend to panic about everything, like whether they started their child listening to Baby Mozart six months too late for the maximum developmental boost, or whether their infant's lack of interest in NFL telecasts indicates they might be gay (or European).

Minor choices, or things that differ from kid to kid, can take on catastrophic significance, and people can project this sense of urgency onto other parents, leading them to assume that the proper timeline of Baby Mozart exposure is as much of a life-and-death issue to others as it was to them when they first found out.

Just so you know I'm not making this up.

So they don't see it as annoying a stranger over a minor problem like having crumbs on their lip, they see it as warning someone that's about to step off a cliff.

As for non-parents, a lot of it is Monday-morning quarterbacking, where things look easier and more obvious when you don't have to actually do them. And when it comes to people offering advice about shutting up a crying kid in public, well, that's because the average human mind isn't equipped to come to terms with a world where turning off that awful sound is not possible. There must be a method. If there is a loving God in heaven, there must be.

Please.

Go to your average general forum/newsgroup/mailing list and look for a discussion asking about problems with any Windows machine. Odds are good that somewhere in there, you will find someone suggesting they should have gotten a Mac.

They will do anything to convince you.

Ask about any problem with any Windows machine, and you can almost bet on getting this response:

Even money that their sig contains a quote from Steve Jobs or some kind of smug zing at Bill Gates or Dell or whatever.

Here's how the rest of the thread will play out: 4 helpful suggestions, 2 more "you should have got a Mac" comments, 3 suggestions that end by pointing out this would never happen on a Mac, and 1 guy promoting Linux.

Probably this guy.

Likewise you have this response to "How long will Windows take to install?", or this question about getting a black screen in Windows Media Center, this question about a blank screen in general, a thread about what camera to buy, or this question about popup ad problems.

Not to pin this whole phenomenon on annoying Mac fanboys alone. You'll see the same thing play out if you ask a broad group about what gaming console to get. The Playstation vs. Xbox a*****es are a sight worse than Mac a*****es, and I only don't quote them here because I can't read most of their misspelled leetspeak posts.

You know what the worst thing about having terminal illness is? Oh sure, dying is terrible and all, but even worse is people offering unwanted and often stupid medical advice. This is actually how many people with terminal illness come to terms with the end, because they realize they will at least have rest from all the people offering advice.

It's a very effective way of having the last word.

When author Christopher Hitchens got cancer, he found himself drowning in advice from well-meaning fans. The loopier ones suggested he try granulated essence of peach pit, testosterone supplements, opening chakras by meditation, eating macrobiotic or vegan diets, and even freezing himself cryogenically. Others suggested specific doctors or clinics all over the world that were the only ones that could save him.

Hitchens didn't mention how many people tried to recommend Dr. House, but probably a depressing amount.

Even people with chronic, non-terminal illnesses get this. One lady earned herself a "what the hell is wrong with you?" from a nationally syndicated advice columnist.

It seems like it should be really obvious that pestering someone with plugs for alternative medicine or telling a story about how someone you knew died horribly of what they have is not something most sick people would welcome.

"Oh, my mom had that. It turned out to be a parasite and exploded out of her chest cavity."

But still, people keep going up to strangers and offering cures from herbs to ox-blood to New Age chants, because they see a person with a cane and think they know the exact cure for... having a cane. Like the author of that article suggests, probably a lot of the reason that well-meaning people do this is because they're scared at the thought that there are terrible diseases out there that can't be "fixed". They want to believe that life makes sense and you can live to a ripe old age as long as you use the right cheat code.

"Squats twice a day, everyone, and soon you'll be right as rain."

Other people just have trouble figuring out how to talk to someone with cancer or a chronic illness, especially since everyone's different, but it's really not that complicated, you ask them. They're human beings and can tell you. Maybe they've got a macabre personality and actually enjoy hearing stories about people dying horribly, who knows.

So say someone -- a close friend, a co-worker, a random stranger on a forum -- tells you that they've been having some hallucinations, black out sometimes, are feeling depressed, and find themselves lashing out at people.

(Or paparazzi.)

Do you:

a) Tell them they're just stressed out and they're making a big deal over nothing.

b) Pull out your DSM-IV and diagnose them with Borderline Personality Disorder or another disease.

c) Diagnose them, then prescribe medication.

If you picked any of those choices and didn't consider telling them to see a professional, you have Clinical Armchair Psychologist Syndrome (DSM-IV-TR, 2000) and recent studies recommend 2-5 self-administered slaps to the face until the symptoms wear off.

Slaps should be delivered just hard enough to knock off your sunglasses.

Don't feel too bad, it's a pretty common disorder, especially on the internet, which is really weird considering that's the place where you would have the least information on the people you're diagnosing. One possibility is that on the internet, people's description of their problems is in text form, which makes it easier for us to make a pattern-recognition link with that psychology article or textbook chapter we just read. Also, people cloaked in internet anonymity usually feel freer to go into more detail about mental symptoms they'd normally be ashamed to talk about in person, giving the armchair psychologists more ammo to work with.

"This is the only way I can get off now."

The opposite side of the coin from people who want to slap an official DSM label on every unusual behavior are people who belittle serious symptoms. You see this most often with depression, which way too many people seem to think means "feeling sad." They hear someone talk about how they've been diagnosed with clinical depression and come in with, "Yeah, I know what you mean, I've been depressed before, when my turtle died."

It was a solemn day.

They'll belittle any suggestion of you going to a therapist or taking medication, because they didn't need any of that to get over their turtle. You just need to start thinking about all the people in Africa that are worse off than you (they don't even have turtles to be sad about), and then you'll be grateful for what you have and ditch your pity party. Never mind that actual depression is a diagnosable condition that can be caused by physical chemical imbalances and deep-seated mental issues. No, you just need to man up and shake it off.

Anyway, there is one piece of unsolicited advice that I will give to you: next time you want to give someone some advice about something, maybe think twice about whether you're being a dick about it.

Check out past articles from Christina, in which she ran down The 6 (Wrong) Questions Men Love to Ask About Women and revealed 6 Secret Monopolies You Didn't Know Run the World.