A sexual position involving 3 partners, at least 2 of them males. The set up is exactly the same as the lamb roast position, however the participant in the middle must have a poor gag reflex. While one person is receiving the blowjob end of the deal, the other person penetrating pushes the head of the lamb roasted all the way down initiating a gag reflex. This is commonly quite unpleasant for the blowjob-ee and the lamb roasted, but quite comical for the splasher
Guy 1: last night Todd, Sarah, and I had a three way.
Guy 2: Dude, sweet!
Guy 1: Yeah, well, Todd thought it would be funny to perform a trojan splash. What an asshole