Ok so here's what you do. It's best when the girl's hair is done in pigtails so you can hold onto them. Get her on all fours & get inside her... give her it GOOD & HARD, escalating with her pleasure... get her screaming with ecstasy... then when she's come a few times & she's a little delerious pull out & ease yourself into her ass... Now hold those pigtails & get high up so that your weight is on her back & lift your legs up so that you're literally riding her.
Now say to her, "This is how your sister likes it..." & see how long you can stay on for.
Now say to her, "This is how your sister likes it..." & see how long you can stay on for.