We realize that this is an uphill battle if there ever was one. After all, the tail wag has equaled "happy" for so long, it is hard to accept it as anything but that; it is an association deeply ingrained in human nature.

And yeah, it might be that. But don't assume that a strange dog is friendly just because it seems to be doing its best to achieve liftoff with the sheer force of its tailspin. There's a chance that could be its way of frantically screaming "Fuuuuuuuuck oooooofffffff!" at the top of its lungs while somehow simultaneously flipping you off with all paws at once.

SurkovDimitri/iStock/Getty Images "A middle finger! My tennis ball collection for a middle finger!"

Wait, What?

The tail can send a bunch of different emotional signals, depending on the kind of wag. For instance, look at the height of the tail -- if Spot is holding his tail up high, he's warning you. The motion is meant to be seen from far away, so it's kind of the equivalent of raising his voice ("Yeah, there's a big badass dog over here, back that s**t off, son!"). If the tail is a little lower, he's more calm. If he's keeping it down near the "between the legs" position, he's scared.

Then you also have to consider the direction of the wag. A dog wagging its tail more to the right has noticed something it is cool with and would like to approach. However, if the wagging is switched to the left, it indicates anxiety. All of these nuances of wagging can convey a wide spectrum of different emotions to other dogs from a safe distance. So, yeah, a simple switch of direction can change your dog's message from a loving "yo, I love you, dawg" to a frantic "your stupid monkey face is literally stressing me out, you revolting butt. Come closer and I might freak out."

ruchos/iStock/Getty Images "PICKLES, HOLD MY WEAVE!"

You know, just something to keep in mind next time you and your friends are walking home from the bar dead drunk and somebody feels like patting that dog that's "totally friendly, just look at his tail, bro!"

Wait, What?

This is an extremely easy mistake to make, because for a human, eye contact can be a very intimate and friendly signal. As such, it can seem perfectly appropriate to lock eyes with a pooch in a "we're in this together, buddy" kind of way. It's too bad that a dog views eye contact as a threat, to the point where they tend to avoid this completely when interacting with their own kind. Yes, members of a species that have no problem eating poop in public will avoid eye contact like the goddamn plague, and not just because they know the other dog just saw them eat the poop and they probably have it all over their face (fun fact: a "s**t mustache" actually makes you cool among dogs; ask any expert).

alkir/iStock/Getty Images "I concur."

So when a dog finds itself staring at a human who looks back, it will give them either a direct stare or what's known as a whale eye. It's important to know the difference, if you don't like going to the emergency room with openly bleeding dog bites:

The direct stare tends to involve close proximity and visible tension in the face. As harmless and cute as it may seem, it is recommended that you look away, as this is your dog doing its best to signal that it's not a threat and everything's cool so would you kindly f*****g stop eyeballing, pretty please? As for the whale eye, it usually occurs when the dog is defending an item or location, and consists of an indirect stare where the dog does not meet your gaze but instead looks out of the corner of its eye, making the white of the eyes visible. The whale eye is generally a signal that the dog is not only seriously uncomfortable but may actually be preparing to bite.

neneos/iStock/Getty Images "I'm gonna get so bad-dogged for this."

Still, before you start interpreting each glance as a potential promise-of-death glare, remember to take the dog's entire body language into account. While the whale eye is a direct signal to back off, if you are uncertain whether or not the eye contact displayed is a threat, also observe the mouth and posture. Are the teeth bared? Is the body position rigid? Is the fur raised? Or, more obviously, is the dog growling?

Overall, if you even think there is the slightest chance of a threat, disengage. And for the love of Roosevelt, do not start any staring contests.

And it could be that, sure. Then again, the dog in question could also be attempting a form of meditation to calm the f**k down, or even straight-up mess with your head.

rue_wi/iStock/Getty Images They can do only one yoga position, so they need something to help unwind.

Wait, What?

A dog may yawn out of exhaustion, the same way we do. But sometimes, a fearful or scared dog might express its state of mind by yawning in an exaggerated way, not unlike we described earlier. Canine behaviorists think that this is a form of self-calming, much like you might try to unwind with yoga or, more likely, Scotch and a GTA V rampage bender. Only, the dog doesn't need such cheat codes into calming down its brain. The self-calming theory suggests the dog's gaping yawn is meant to lower the temperature of arterial blood and literally cool its head.

Yet another theory, which paints our doggy friends in a slightly sneakier light than most would assume, suggests that when dogs see humans yawning, they mimic the behavior as a form of empathizing and relating to their masters as an attempt to adapt to their environment.

Digital Vision./Digital Vision/Getty Images "I gotta tell you, Food-Man, sleeping 14 hours a day really takes it out of you."

Yes, this means that when a dog yawns, it might just be tired -- or it might be imitating your yawning, specifically so that you do that "aww, he thinks he's people" thing and maybe feed him more of those delicious sausage links.

We feel guilty for not walking our dogs as often as we think we should. They're the descendants of wolves, of course they need exercise! So who could blame them for tugging a little as we head down the sidewalk? They're simply excited to get out and about! What's wrong with that?

Nothing, really. That is, unless you count the confused animal slowly choking itself at the other end of the chain.

DavideMombelli/iStock/Getty Images "You remove my balls and then act surprised when I need to go to extremes to get off?"

Wait, What?

Right off the bat, pulling is a sign that your dog has no idea how to use a leash, so there's that. Dogs aren't born knowing what a leash is; they actually have to be trained to go for a walk without straining against what the dog must think is a weird invisible tractor beam humans project when outdoors. There are plenty of guides online on how to do it, including the words we just linked up there.

But the tugging can also mean your dog may be trying to assert dominance. It's not that Fluffy is being a dick -- hell, dogs were bred and domesticated specifically to follow orders. But this is what a dog does when it doesn't have a leader -- it graciously accepts the throne you've unwittingly abandoned. It takes charge of the walk. If that means dragging around a 175-pound human using its own neck, so be it.

Ingram Publishing/Getty Images "Come with me if you want to HOLY s**t I SMELL FOOD SOMEWHERE!"

This, by the way, is an extremely bad thing, mainly because it can seriously hurt the dog. Due to years of wearing what's essentially a really tight necktie, dogs may have become desensitized to the constant strain on their neck, which will cause them to pull even more if the behavior is left unchecked. This, in turn, will damage the dog's trachea in the long run.*

*Note: Dogs are not very smart.

"Aaaaargh! Look what the beast did to me! It should be put down!"

MoustacheGirl/iStock/Getty Images "I've only got four months left of sad-puppy-eyes-ing my way out. I need to make them count."

It's an all-too-common scenario that is often bad news for little Barkley, especially if he happens to be a pit bull or some other breed with an aggressive reputation. It's also one that could be easily avoided by realizing one simple thing: that grin on the pretty doggy's face isn't a smile.

Wait, What?

This one might seem pretty obvious, seeing as teeth are what a dog defends itself with, but a shocking number of otherwise sane and responsible pet owners still seem to think that their dog is smiling like a person when it's showing teeth.

CREATISTA/iStock/Getty Images You know, just like how humans greet by pulling a gun on one another.

Here's a quick rundown on the fairly limited expressions of the gaping, predatory maw that is the mouth of your precious pooch. A happy dog generally has its mouth closed or partially open, with no visible teeth. If the mouth is widely opened, the dog might just be cooling itself down by panting. If there's a visible array of teeth, f*****g walk away.

A dog pulling its lips back to bare its teeth might look a bit like it's smiling, but it's actually just keeping its weapons handy. There are several variations of toothy "grins," all unleashed because the dog is feeling frightened, angry, or outright ready to attack. Hell, an aggressive dog can even communicate its intentions via an "aggressive pucker," where it puffs its lips like it's about to smooch you. In this event, do not attempt to kiss it, and even if you do, under all circumstances refrain from Frenching. You don't want to explain that one in the E.R.

monkeybusinessimages/iStock/Getty Images "Yeah, let's see you 'I slipped in the shower' your way out of this one."

The closest a dog can come to physically smiling is the "submissive grin," where the dog curls its upper lip to display front teeth, which ironically seems a lot like a threatening gesture but is actually just the dog's way of saying it feels intimidated and poses no threat to the challenger.

Pareidolia is a fun thing when it comes to seeing faces on the moon and shapes in the clouds, but this is one occasion where it is very much an enemy. It's no surprise that dogs can use their faces to signal emotions like humans -- hell, a recent study revealed even mice can do the same thing. However, just because several species signal emotions with their faces, it does not mean that each species uses the same signal for the same reason or to communicate the same things.

RayTango/iStock/Getty Images Except for cats, for whom all facial expressions mean the same thing: contempt.

Look, we're not saying that your dog doesn't love you or anything. It totally does. But if you love it back, take time to learn how to speak its language.

For more reasons you're bad for animals, check out 6 Stupid Things Pet Owners Need to Stop Doing Now. And then check out 28 Real Animal Abilities You Won't Believe.