When you prop your partner up and then sit asshole to asshole with them and take a shit into their gaping rectum while you're both masturbating.
Bro 1: Bro last night, guess what I did with Mikayla
Bro 2: Bro was it a Perf Dirk
Bro 2: Bro ew what the fuck? You know Perf Dirk is for the boys