A sex move that involves two guys getting it up the ass in weird ways.
Eww, I heard Jamie was Grand Slamming Jordan last night!
by Forgott|e|n July 30, 2008

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When a woman orgasms so intensly she squirts, pees, shits and even starts her period.
That wasn't an orgasm, that was a grand slam.
by squirty girl February 18, 2012

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group sex
I hit a "GRANDSLAM" last night!!!!
by me mee November 14, 2003

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anal sex
4th base?
No. Grand slam! Right in the ass!
by bcimchuckbass February 22, 2014

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A game usually played at high school dances, who's objection is to make out with at least one person from every grade, including your own. Another variation of the game is that, in order to win, you count each person you make out with by points. Someone in your own grade, for example, could rank as lower points than someone in the senior grades. The person with the most points win.
Virginia: We should totally play Grand Slam at semi tonight.
Jared: I definitely won Grand Slam; I'm only a niner and I made out with over 12 grade twelve bitties.
by Virginialikeswomen February 21, 2011

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Rock band former by Phillip Lynott when Thin Lizzy split up. Toured Europe continuously but never recorded anything due to Lynotts untimely death.
Grand Slam bootlegs are very sought after by collectors.
by black flag May 29, 2004

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A foursome. Where as 'hitting a home run' means scoring with one chick, a grand slam means four runs so four chicks.
"I hit a grand slam home run last night."
by matt January 05, 2004

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A male performing a one night stand with a female successfully penetrating, and ejaculating in every love hole, before going to sleep.
"Hey man, did you get with that chick last night?" Ya man, I hit a grand slam on her.
by Mr.nunes March 10, 2009

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