A2M is a shorthand way of referencing ass-to-mouth sex, which is the act of fucking a hot chick’s butt then having her suck it immediately thereafter. This designation for ass-to-mouth developed on the internet, mostly in Usenet newsgroups, in the early 90s. You can confirm this by visiting the rec.arts.movies.erotica archives.
A2M
These 3 ATM babes suck A2M cock in their full episodes at Ass Traffic.
Ass To Mouth A2M - The nasty anal sex act that’s freshening the breath of hot chicks everywhere. If you need to cum, and you need to do it now, you need to watch some A2M porn, my man.