While fucking a girl in the pussy, you stretch your nutsack skin out far enough, as to allow you yourself to "ball-fuck" her anus, (insert sack in anus). Yvette loves this.
"Yo dude last night I was banging Yvette and she was like, Shpackle my incredibly dirty anus!, so like... I did."
"Awesome dude! Yvette's ass has been shpackled more times than Sean has jerked off in Ricky's ear!"