1 definition by GangstaPornBitch
When a man is fucking a woman doggystyle and "accidentally" slips his penis into the woman's anus, and she responds by turning her head around, arching her back, and making a sound similar to a dolphin or porpoise - "eeee! eeee!"
Dude, last night I tried to slip it in Katie's ass, and she totally started porpoising - it was hilarious.
by GangstaPornBitch February 9, 2008