An acronym: Bare Back Ass To Mouth.

Slang mainly in prostitution circles and used to describe what a particular call girl will do. In this case Anal sex without the use of a condom followed immediatly by oral sex.
An actual craigslist ad:

Let this young lady charm your heart with all her special talents. A brunette with blue eyes, who could resist such a beauty. Availiable appointments now.

$800/hr- bbatm
$600/hr- bb
$450/hr- greek
$300/hr- full service
by Panic! InMyPants November 16, 2006
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