B-52 Bomber
When a guy with a hard-on or a girl with a strapon stands on the edge of the bed and the other person is flat on the floor spread wide open. You jump off and land so deep it feels like you're inside a toilet.
My boyfriend tried to do the B-52 and landed so hard I thought he broke his foot.
I did the B-52 with my girlfriend and she screamed so loud the neighbors called the cops.
My sister tried the B-52 and ended up with a paper cut from the bed sheet.