Top definition
Means "F*ck It Senior Year" of High School.

Strictly for senior use ONLY.
Stupid sophomores try to Disguise it as Fi Sophomore Year
But they are just trying to be cool. And Failing.
Senior One: I got so drunk last night I don't even remember!
Senior Two: Dude me too!
Both: FISY!!

Sophomore: FISY
Seniors: *Jump the sophomore*
by carebear sheep April 24, 2011
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