Why is it that annoying people on Facebook say that they're ugly, specifically to irritate others?

[Cameron]

It seems like on Facebook, or anywhere on the Internet really, people call themselves ugly exclusively to tick off other people. Then, when someone tells them they aren't ugly, they just respond "You're just saying that" or "I am too ugly". You know what my counter-response to that is? "Okay, fine. You're a useless, ugly piece of trash. Is THAT what you wanted to hear?".

[Joey]

Haha that's an awesome response I'm gonna do that but they do that because they want attention. That's all really.