When anal sex occurs and the fuckee has not cleaned their anal cavity properly (i.e. a euphemism for shit).
Dude! Why didn't you get all that mud bunny out of your ass before you let me put my dick in?!
by folkyboy August 02, 2008
Hardcore female mountain bikers.
"Those are some serious mud bunnies." - said after watching 3 women fly past you after they clean an enormous drop that you just chickened out on.
by sir laughalot December 21, 2012