Debates rage about the interpretation of certain nightmares (with a card catalog of dick-centric opinions available on Yahoo! Answers alone). But while we may not agree on what the dreams and nightmares mean, we're pretty well settled on what the common ones are. Here are five of mankind's bad dream greatest hits, with non-dick-centric theories as to why we have them.

Forget Freud and his fancy-pants dream analysis -- when it comes to understanding what common factors in the human condition could bring about such a Lynchian nightmare, look no further than Thomas Hobbes. Hobbes brought the gavel down on this in his seminal work Leviathan (1651) when he stated that life is inherently "solitary, poor, nasty, brutish, and short." Frankly, life sucks for everybody, and it could end at any instant. Instead of making the most of our brief tenure on the planet, we're eating varying levels of crap as calendar pages rapidly fall to the ground. Like our teeth. With which we have had to eat all this crap. Or, you know, without teeth, your nourishment will be limited to McDonald's shakes and you'll die.

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"Our milkshakes bring all the boys to the yard ... the graveyard."

It doesn't matter if you're doling out cologne in a strip bar bathroom or you're Elizabeth Dole, it's likely you'll be as toothless as Thomas Hobbes at some point in the dead of night.

You're sitting at a desk, blue book and pencil in hand, armpit-soaked and petrified. There are 15 minutes left on the clock, and your book is blank. Or you realize you missed this class all year -- just flat out didn't show up -- and now the questions on the test are reading like Russian. Oh God, it's Russian 401!

It'd be time to panic, if it weren't a nightmare. After all, you've been banned from entering any institution of higher learning for what -- 10? 20 years? So why freak out about tests when you could be freaking about something more interesting, like how you will ever eat your way out of a giant strawberry pie?

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"You are the only one who can do this. You are the chosen one the diabetic elders prophesied."

It's because you've made at least a marginal amount of yourself and you're afraid of losing it. This is a nightmare of anxiety over personal and professional accomplishment, and it tends to plague people who have already done well (e.g., enrolled in Russian and didn't drop it). No matter the success we achieve, we never get rid of the insecurity that one day we won't measure up to expectations. And unless you went to some hippie school, this is one place where everyone's performance or lack thereof was evaluated in writing.

So, if you want to avoid sharing this one with your fellow man, best not have any ambition or goals whatsoever to begin with.

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Which may explain how hobos can sleep anywhere.

Contrary to popular belief, you will not die if your terminal velocity comes to a conclusion during a falling dream. Or, at least no one who did die during one of these REM bad times bothered to come back and tell the rest of us about it. But, hey, it's out of our control. We're not the boss of those ghosts.

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"No, the falling dream didn't kill me. The Nic Cage go-kart one, on the other hand ..."

The fact that humanity is plagued by this one proves that we need to chill the hell out. Just don't go so far as taking on a full "The Fates will provide" attitude at work. The Fates are not skilled at spreadsheets and coding.

Only 33 percent of Americans describe themselves as "happy." If you're in the other 67 percent, chances are one of the following applies: You've been at the same job way too long, and it sucks. Money's always a problem, but there are no non-felonious options to make more. You can't stand your significant other, but change makes you more uncomfortable than stagnation. You have way more bratty kids than you ever thought you'd have, and Grandma's not much help anymore because she's getting up there. The point is that you know your life is one great big confining rut -- you feel it, every waking moment of every day, and you don't do anything about it. And then you hit the hay, just to escape for a few hours. But after a terse dream-visit with Grandma, who's completely sick of your hell-spawn and for some reason now carries around an assault rifle, you find yourself in a room, and the walls start closing in -- closer and closer and closer -- like a Death Star trash compactor. There's no way out. You're trapped.

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"I'll get you for this, Grandma! You're going to the home we saw on the news!"

And that's pretty much it. This one is kind of embarrassing for humanity, what with its trite and obvious interpretation. Then again, it's also pretty refreshing after the whole freaky "teeth falling out" thing.

It's not just you. Most of us feel like we'll be unmasked as a fraud at any second, whether it's because we are actually lousy parents, b.s.-ed our way into a job, or wear a man-girdle to make our clothed body appear marginally palatable to society at large.

Occasionally the "nudity nightmare" comes in a combo pack with the "big test nightmare" (which allows you to pick at your failure AND fraud scabs in half the time!). So tonight when you're snoozing, if you find yourself wedged into an old school desk, marinating in a pool of your own naked butt sweat, know that you're not alone.

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The downside is having to fight other naked dream people for the non-lefty desk.

As that American Anthropologist article said: "Typical dreams mark a public domain. They intimate a common bond between us." And that bond is species-wide self-loathing.