An awesome sexual manuever! have sex with a girl, cum all over her insides make it sloppy, a fucking sloppy mess, but leave your dick inside, eventually it will get soft. with your soft dick in the girl ( it's good to leave it in there overnight for best results) just pull it out as quick as humanly possible. sick! ur dick has shrank inside her dilly-hole (a.k.a. vag) you will have created suction cause ur dick to stretch and finally give way and come snapping back into ur testicles at starship-enterprise-warp-speed hittin ur nuts so hard that for some reason u get sexually aroused -- rinse (or not :D) and repeat!
Dude, i slept of lafawndah's house and totally sling shotted myself like 7 times!