When you put your mouth over a guys penis when he is soft, as if you are deep-throating, and then wait for him to get hard and he pelvic thrusts with a force greater or equal to the eruption of Mt. Vesuvius, impaling ones throat.
Alternatively,
When you force a person's mouth over your penis when it's soft and you become hard thus causing them to gag and tearing their throat lining causing a series of recurring hospital visits.