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when a male or female is fingering his or her woman:
he/she places 4 fingers inside the girl with a flat hand resembling a sharks fin. then making wave like motions with the hand when all of the hand other than the thumb is inserted.
shark finned fuck out that bitch last night!
i was hefty shark finning at the weekend
by RamboJambo123 August 11, 2009
When you float on your back in a body of water with an erection that sticks out like a shark finn.
I'm gonna go shark finning around that bitch in the deep end of the pool.
by D-Rye August 05, 2013
To swim backstroke with an erection.
'Did you see Ralph? He was totally Shark Finning it over that lifeguard.'Said Paul.
by SickyMike October 17, 2014