I've got to copy Sportbikes.net. Theres an excellent thread going on there that I check daily for belly laughs.
I don't even know where to start as far as reposting their stuff, however...I'll start with some of my favorites and post up whatever other funny stuff I find. You guys should contribute as well!
Here's the original thread. Prepare to be entertained for hours. (You have to register to see the majority of the pics).