Short for Foster's Home for Imaginary friends. When kids get too old they don't need imaginary friends anymore so they stay at Foster's until they get adopted by another child (presumably with no imagination of their own).
Foster herself is a little old lady who still has her imaginary bunny friend.
Mr. Unicorn, we regret to inform you little Stacy is dead, so you'll be staying at Foster's from now on.
by unicorny July 30, 2006
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foster is the hottest man to walk the earth. period.
girl: foster date me!
Foster: sorry, im already dating 1000 girls.
via giphy
by EXDA March 26, 2019
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In regard to video games, to shoot an opposing player in either the crotch or ass. Also referred to as "Buttering" as in the episode of South Park where Butters shoots everyone in the crotch.
Guy 1: "Dude, you totally just shot him in the dick!"

Guy 2: "FOSTERED!"
by Arkem3 June 25, 2011
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a word for someone who has more then one STD.
I know i have a foster on my cock after hooking up with that slam pig the other night.
by Barry Gorman October 11, 2006
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foster: people with no parents

parents dont want the kids

kids live with their grandparents
by donthavetoknowme1 June 10, 2011
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Super athletic (mostly at football) and gets all of the laddies but only sticks to one and gets attached too easily.
Wow, that boy can really run the ball... yeah he must be a Foster.
by Dan Hibbet December 05, 2016
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