The Sphincter Thump is a more humane / less illegal derivative of the Donkey Punch. While fuck'in Doggy Style the man reaches down and thumps the woman’s anus as hard as he can with a flick of his finger. The reaction is that the woman tenses up and greatly enhances the mans climax. (*Note the most effective thump is to bend ones middle finger back using the thumb on the same hand. Once cocked aim for the Brown Eye and let it fly).
Do you want all the benefits of a Donkey Punch without the trip to jail and rape investigation? Then try the smart man's way to muscle seizing pleasure, the Sphincter Thump.