While in the missionary position, the male party pulls out before climax and shoots his load all the way up to the open mouth of his female partner. This is akin to the exhaust port shot that destroyed the first death star in Star Wars: A new hope.
"Almost there ... Almost there ... HITS AWAY!"
"Dude, did you achieve an exhaust port last night?"
"Negative, negative, it didn't go in. Just impacted on the surface."