Grader Box 

While have sex in the missionary possion the male stands up, while still coupled, and punches the female in the stomach causeing her vagina to contract, then quickly backs up while she is stll clinched, like a tractor dragging a grader box

Matt: "Hey Troy, you owe me some new sheets
Troy: "Why is that?"
Matt: "I ripped through my sheets giving your mom a Grader Box, last night."

Grader Box by fishermenrock September 20, 2012