is it playing drums on a butt, or a code word for farting, or some deviant sexual term?
I’m not sure if there’s a straight answer here, so I’ll put it in IMHO rather than GQ.
That’s it, on the…errr…nose.
I love this board.
See also Howard Stern’s Butt Bongo Fiesta. No, really I couldn’t make that up if I tried. The link is safe for work, but NOT the video.
I have given my niece the nickname Baby Bongo Butt because you can play them like bongos. 
In tonight’s performance, Kirstie Alley will be playing the part of the kettle drums.
The best part about threads like this is imagining the OP thinking about the issue long enough that they finally think “Dammit, I’ve gotta find out what this is.”
And they’re quite entertaining once people start replying.
3 minutes from question to answer! And I didn’t know it either.
To make it thoroughly satisfying, tell her boyfriend about it at 16. 
They’re not really the best thing for rudimental drum features. Also, apparently drumsticks are a little too abrupt for smooth butt-bongo playing (if not missing the point entirely).
So I hear, anyway.
We refer to it here as " Baby Butt Bongo" cause baby butts are soooo cute.
If this is a deviant term, Mr. NurseCarmen, I will not be happy.
Not sure if I should admit this here, but I’m a butt bongo…virgin. I did find this brilliant photo though. Safe for work. At least my office.