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1 definition by MagnumTT

A sex act. While having sex doggy style a dude jizzes in his hand and hops on the girls back like he is riding a horse. He then reaches around and puts the hand he just jizzed on over her mouth and yells OAT BAG! The other hand can slap the ass, or remain idle.
Stephanie is super pissed at me for giving her an oat bag and slapping her ass last night.

Nothing is better after hot sex like a nice oat bag to hold me over until next time.
by MagnumTT January 13, 2011