Literally, your butt. Or bottom, booty, bum, rear, buttocks, derrière, etc.
Kelsey: Dude, don't be checkin' out my fessis!
Philippe: I'm sorry, I couldn't help it!
Kelsey: okay, well, don't let it happen again or i'll have to kick your fessis.
by Kelseysomethin' April 1, 2009
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the art of going out on the piss and getting fucking messy.
wow,last night i must have had 20pints of beer! i was fessy!!
by shane cross September 9, 2008
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the worldsbest person you‘ll ever know
dude i love fessi!
by reingardios November 18, 2018
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