Usually reserved as a "finishing move" during heterosexual intercourse. While the male and female engaged in Missionary Position intercourse the female lowers and closes her legs and the male then straddles her thighs an continues to thrust, making more contact with her tightened vaginal canal and clitoris thus increasing both the chance of and intensity of the female's orgasm. A secondary benefit is if the male is going to "pull out" he is in the perfect position to dump his load all over her stomach and breasts.
Frank and Renee were reaching the point of no return when she moved to Legs Down Sex so she could cum hard and fast before jacking Frank's crank all over her tits.
by prohibitedweapon July 20, 2012