Great message, that our society should stop worshiping airbrushed perfection in magazine adverts. Silly, but hell, it's humanity. How humane, ne?

Anyway, the one gripe I had with this is your grammar (specifically, your use of their/there/they're).

THEIR: a possessive; "Their hearts were broken at the mere prospect of breaking up."

THERE: referring to a place; "I left the pickles over there by the bench."

THEY'RE: they are; "Uggs? Oh my god, they're ugly!" (Which they are XD)

Other than that, good job!

A reply to a simple pan song should be more like this: Shut the hell up/ And smile, you bastards/life doesn't suck/ You just think it does/ No likes whiners/ So stop doing your thing/ Because, you know what else?/ Pierre really can't sing. Nice poem, though. But yeah, it is THEY'RE. Short for they are. Other wise you're saying "Belonging To Them".

You've got a really good message, but you used the wrong homonym through the whole thing *winces*. Their should be "they're"... when you read it, try to use "they are" in the place of the word to know which one to use... if "they are" makes the writing still make sense, the word you're looking for is "they're," not "their." :) Hope this helps. Good poem... again, it's got a really strong message, and that's great. :)