A man that is developing a bald spot on the back of his head resembling a baboon’s or chimpanzee’s ass. This phrase works best if the person combs his hair over this balding area and thinks nobody notices he trying to hide it!
Check out the "monkey butt" on that guy or "nice monkey butt".
by LisaD143 August 02, 2005
A chafe recieved between the upper thighs and asscrack brought about by sweaty activities such as walking back and forth or working out of doors. Produces a Baboon-like rash on the buttocks.
"Man, I got a serious case of monkeybutt bartending tonight!" or "Landscaping gave the rudest monkeybutt yesterday!"
by Mick September 21, 2003