4chan is like a less corporate newgrounds, but with about 50x the user base.
4chan is where the internet gets its jokes from. Rick roll? Chocolate rain? 4chan.
4chan is the place where anything goes. Anything.
4chan will fuck you up. And you'll like it. Never seen a picture of a child whose head has been run over with a funny message on it? Now you have.
4chan is a place where you can get porn featuring man on man, woman on man, woman on woman, man on beast, beast on man, woman on beast, beast on woman, child on man, child on woman, child on child, or child on beast.
4chan makes fun of the rest of the internet. Know what they call this place? Faggrounds. Yep.
4chan hates the rest of the internet, and the rest of the internet pretends they hate 4chan.
Most importantly, 4chan is down. So I'm on Newgrounds.