It’s called Mad Xzibs, and it goes a little something like this:
SUP DAWG, WE HEARD YOU LIKE(D) ______, SO WE _______ ______ IN THE _______ (SO YOU CAN ______ WHILE YOU _____).
I guess it’s been around for awhile, so much so that there’s a controversy over using “SUP DAWG” and “YO DAWG,” but I just found about it from an old Urlesque article, so here it is. These are two of a few that cracked me up. The Urlesque page is the better of the two since its condensed, but the Encyclopedia Dramatica article is not without its humor in explaining more of the history.
A few of my favorites: