An incredibly elaborate sex act requiring precisely three people. Person A takes a very hot shower so his balls are hanging rather low and then scoops his balls up and on top of his boner. He then sticks his boner between his legs and closes his legs so that his balls are up front and his boner is sticking out back.
Person A now waddles backwards and sticks his boner into Person B's ass/cunt (cannot be mouth). Person A does an abbreviated squatting motion so as to fuck Person B, but all the while Person A is keep his legs closed and his balls up front.
Just prior to climax Person A will point to Person C and scream 'Bloody Mary'! It is at this time that Person C, who has been an innocent bystander til this point, takes aim at Person A's awkwardly exposed balls with a paddle or baseball bat.
Only moments before Person A blows his load, Person C will strike Person A in the balls so that upon busting, Person A will blow a bloody cumshot into Person B's ass/cunt. Thus completing the 'Bloody Mary'.
Larry: "Hey Lawrence, I couldn't help but notice in the locker room that your balls are black and blue. You OK?"
Lawrence: "Oh, it's no big deal. Me, Rachel, and Rob had Bloody Mary Sex last night. And I'll tell ya what, Rachel can really swing a baseball bat hard!"