Lolcats. Honestly, it virtually defies explanation. Check out some examples at I Can Has Cheezburger?. No really, it's mostly safe.
Framer, CD Cover, Wallpaper, Movie Poster, Calendar, Badge Maker, Lolcat Generator, Pocket Album, Cube, Trading Card, Photobooth, Motivator, Bead Art, Hockneyizer, Pop Art Poster, Mosaic Maker, Jigsaw, Mat, Billboard, FX, Magazine Cover, Color Palette Generator,
I know, right? It's a lot to take in. Go slow.