When your fucking a girl standing up from behind, and you cum so hard it blasts her off your dick like a roman candle firework.
If one is skilled enough, they can actually emulate the action of a real roman candle and do this several times in a row (with a different girl each time of course, since the girl is usually injured on her way back down to earth)
dude#1: I was going at it doggy style with that girl from the bar last night, and I shit you not, i actually came so hard, that she "rocketed" off my dick and into the wall....is there even a name for that?
dude #2: holy shit dude! you perfectly executed the ROMAN CANDLE!!! you gotta show me how....