Korean Ribbon Fuck

During hetero intercourse, the female has a length of silk ribbon, about 2 feet long, with small knots tied along its length at about 3 inch intervals, and while the male is fucking her vagina, she is slowly, lovingly inserting those knots one at a time into his ass with her fingers, then when he starts to cum, she yanks the full length of the ribbon and all the knots out of his ass, thereby intensifying his orgasm.