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".
An often shy, comforting creature that lurks around campsites. They forage for food, especially brownies or peanutbutter whilst campers are away from their tents. A Monkeybutt is a carefree, yet hyper animal who enjoys climbing tree's and often has a naughty side flashing their butt's to attract female attention. A Monkeybutt is rare creature, but enjoys attention of sorts and will be your friend for life.
Once you find a Monkeybutt, they will never leave your side.