BECAUSE IT'S THE MOST AWESOMEST THING IN THE WORLD. And it makes school fun. And it's hilarious. And just really popular. And 당신 it inspires awesome modified rage faces.
We like it because its hilarous. Someday 헤타리아 will rule the world.
Oh and I noticed in 코멘트 당신 aksed what it was. It is a show were each character is based on a country of the world. Ech character is based off the countries stereo types. 헤타리아 mainly takes place in World War Two, like when Hitler was killing jews. O_O
BECAUSE IT PWNS YOU!!!!!!!!!!!!!!!!! jk. well its basically about world history and the characters are humans based off countries and each character's personality is based off stereotypes of that country. its also really funny and i suggest that 당신 watch it. just look it up on youtube.
It's an 아니메 that spoofs WW2 and depicts the countries as idiotic retards (most of which are male, though there are female characters).
Unfortunately, the countries are very poorly stereotyped, and the humor isn't exactly what you'd call "humorous".
You're better off watching "You Nazty Spy", which is an episode of The Three Stooges that spoofs Hitler and the nazis (interestingly, the Stooges themselves were jewish). UNLIKE Hetalia, 당신 Nazty Spy is actually funny.