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8.
A term more commonly used in the UK, it is simultaneous defecation and vomiting, usually upon oneself. Normally occurs post heavy-drinking.
Did you see that bloke who just Grandslammed in the bathroom?
by Chewy L. May 20, 2006
 
9.
A Grandslam is the upgrade of a Strikeout. Whereas a Strikeout is consumed in the order of marijuana, liquor, and beer, a Grandslam is performed by conusuming a line of Cocaine to leadoff the order. So it goes line of Cocaine, Bong Rip, Shot, Beer Chug, Release smoke. Grandslam.
Jack took a shotgun last night and was a badass until Ryan outdid him by pulling out a line and introducing us to the epic grandslam.
by big_tymer8067 December 11, 2011
 
10.
Taking a large hit/toke from a bong/bubbler/vaporizer holding the smoke in the person's lungs while taking a shot of liquor then chugging a beer; finally doing a line and blowing out the smoke.
*Almost impossible*
"that fool did a Grand Slam last night and straight up died; but we all thought it was ill to watch!"
by pappyinww2 April 06, 2010
 
11.
When you have sex with 3 different people in 3 consecutive nights, or 3 different people in one night. It's called a grandslam because you made it to home with 3 people.
Dude, I've got a Grandslam lined up for this weekend! Christy on Fri, Susie on Sat, and Becky on Sun!
by Bayushi_Koso September 09, 2011
 
12.
a common sex act in the colorado and rocky mountain area in which one sexual partner purchases a grand slam from Denny's restaurant, places the entire meal in his or her partner's ass, and eats the entire thing seasoned as preferred...hot sauce is commonly recommended
I was hitchhiking with a trucker, when we became really hungry. As we passed by Denny's, we decided the best way to fix our qualms would be to share a grand slam.
by rossthehaus June 07, 2011
 
13.
The act of lodging the wide end of a tennis racket into ones rectum.
After I was done cumming on Jenny, I finished her off with a Grand Slam.
by TheCerealKiller June 16, 2014
 
14.
anal sex
4th base?
No. Grand slam! Right in the ass!
by bcimchuckbass February 22, 2014