A foursome. Where as 'hitting a home run' means scoring with one chick, a grand slam means four runs so four chicks.
by matt January 6, 2004
To awake one fine morn, and verily discover one's matress resembling a ordinance survey map with a rather warm chocolate log spread all over it as well as spew on your face and pillow.
"I do not think she will want to see me again after I came home totally ringbolted and grand slammed the bed, although your mum is a bit of a dirty slapper."
by Terry Fuckwit June 24, 2004
When you pull your penis as far back between your butt cheeks(chicken in the rough), and put it against a window to surprise someone
by Joe cock February 22, 2017
A highly prestigious award given to the team who finishes UNDEFEATED in the 6 nations rugby championship. In other words, NO TEAM COULD BEAT THEM, THEY WERE TOO GOOD FOR ANYONE, NO-ONE COULD MATCH THEM FOR CLASS, SKILL, FINESSE, PACE, AGILITY, PASSION AND SHEER BRILLIANCE.
by God HelpEnglandInTwickenham June 23, 2005
when you are heaving sex with a chick, take out a baseball bat and shove it up into her anal cavity, then pull it back out and hit the chick in the face with it.
by john February 14, 2005
As with the other baseball references to the bases (first base, second base, and so on) the grand slam refers to having anal sex. Since it is one up from a home run (just vaginal sex), and doesn't usually happen quite as often.
by Chris11 November 22, 2007
involved with sexual intercourse. you start off knowing that you are going to round all of the bases. As you round all of the bases, you waive to the crowd like a pro. you take your time to round all of the bases to get the full enjoyment out of the moment. Then when u get past the home base, you high five your team who are all lined up from the plate to the dug out - and the party doesnt stop there.
by ummmm.. what tha May 30, 2005