But here are five facts you didn't know about our furry, rodent friends.

Number one, New York City may have the biggest rat infestation in the world.

If you haven't seen the hilarious but horrifying videos of New York rats on YouTube,

you're gonna wanna check them out.

In one of them, a person is asleep on a subway bench while a rat climbs up his leg and onto his lap.

NYC has declared a war on rats, and budgeted more than half a million to an anti-rat program.

Number two, rats can swim up the pipes into your toilet bowl.

It's a rare occurrence, but a frightening reality in towns with older sewage systems.

Rats can get lost in the pipes and tread water for days, seeking a way out.

If you ever encounter one in your toilet, just know that it's very tired from swimming, and probably won't be aggressive.

But still, I mean, don't touch that.

Number three, there is a Rat Island off the coast of Alaska, and it used to be full of rats.

In 1780, a Japanese boat shipwrecked there and a few rats who were on board quickly overran the native species, including some endangered birds, like the bald eagle.

But in 2010, the US Fish and Wildlife Service eradicated the rats on Rat Island.

So now the name is just ironic, and very cool.

Number four, a rat's front teeth can grow five inches in a year.

That's why they're always gnawing on things, to grind them down.

The teeth can grow fast or slow, depending on the rat's diet.

And rats don't get cavities because they just get worn away as the teeth grow.

Number five, scientists say that rats can laugh and they can dream.

Dr. Jaak Panksepp from Washington State University says that rats emit a high frequency chirp when they play together, or when a hand tickles them.

And at MIT, scientists say that their lab rats were dreaming of running a maze.

They recognized the same brain wave activity in sleeping rats that occurred in wakeful rats that are running a maze.

Have you ever seen a rat in your toilet bowl?

Tell us your story in the comments.

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