Reference for when two people engage in anal sex.
Slang short hand for when people are engaging in anal sex. Usually referenced due to the way the numbers look, the rounded edge on bottom, the other rounded edge on top of the other bottom. 66.
Simple play on numbers, and bit of code.
Noteworthy: Many numbers are being used, as sort of a secret code, or one that isn't easily picked up by the casual observer. Not like Polari, which was a sort of code using words with hidden meanings.