The act of being taken down an alley, and and having sex doggy style...which then results in your face being scraped against a wall. Leaving bruising, scratches or sores.
"Oh mate you have no idea what I got up to last night"
"You can't top me I got alley faced"
"I am totally getting alley faced tonight"
"That'll leave a mark"
"Alley face me, you prick"