Boston Angel

The act of two adults pressing their anuses together and passing gas, frequently back and forth to one another.

Bostonian #1: Did you get any action last night?
Bostonian #2: Ah, bro, I totally gave her a Boston Angel!
Bostonian #1: Ah, sweet, bro! Did it smell bad?
Bostonian #2: 'Course it smelled bad, dude, I had nothing but Natty Ice and chowdah for three days.