When you are laying down and have an erection. A large, 400 lb woman walks into the room and jumps on the erection and starts having sex with you.
Guy 1: Dude, Sydney jumped on my erection last night and she weighed like 400 lbs!

Guy 2: That's called a Hiroshima Shockwave!
by FIRESTORM221 April 12, 2011
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