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When two people have sex, And the third person video records it.
Bob: Yeah, I had a 3sum last night!
Tom: Was it good?
Bob: The third person, Was such a good recorder, It could have been a porno!
Tom: When you make it A movie, I'm buying it.
by BlahhhhhhBiiiittchh! January 14, 2010
where 3 ppl, usually either 2 males and a female or 2 females and a male have sex together, lots of diff postions and is quality to do !!
u blow me girl and u the other girl sit on my face
by know it all February 17, 2005
Engaging in sex acts with two other people; either MMF or FFM. Usually used in text speak.
Wanna 3sum 2nite?

Most peopl fantasise about 3sums
by freakshow July 01, 2005
When three Fuck hopfuly when the guy gets 2 gurlz at once like me all the time
John gets his cock sucked by traci while eating out shawna all that time
by John OD November 02, 2003