A descriptive term used by men to complement the posterior of an attractive female. The term was coined due to the relative similarities observed between the capital letter "A" and the angular proportions of certain females posterior regions.
AJ : Check it out. Chick in the blue jeans has a nice fucking A-frame.
CJ : A- frame??? I'd really like to know how you thought up that term and what the fuck it has to do with girls backside.
AJ : It's easy. Look up one pant leg to the crotch move your eyes over that area then run your eyes down the other leg.
CJ : Fuckin' A. Good call.
An A-Frame is when three people (usually two guys and a girl) engage in a sexual sort of threesome. Usually the two guys stand facing each other with the girl between them. With the girl still in the middle, she is giving one of the guys head and the other has himself inside of her. They do this at the same time, switching terms and positions. Sometimes the two guys place their hands over there head towards each other (like in an "A" shaped way).
Since I can't really show you a picture of an A-Frame, the definition pretty much sums it all up.
When two male friends have sex with a woman at the same time, one receiving fellatio and the other in the doggy style position, and they give eachother double hi fives.
"dude, me and kev got matt's norwegian exchange student in an a frame on saturday
a vehicle engine hoist. a substitute can be a strong tree limb, straddles fenders to support engine or drivetrain. can double as a swingset.
Billys car motor is busted and we aint got no big trees in the yard so we rented an A-Frame.