a variation of spooning where the guy is the little spoon (also assuming he is the taller partner. Optionally: might allude to the girl being a farter)
A enjoys his gf jetpacking him...
When the male is the shorter partner in the sexual encounter and is performing intercourse from the back.
"Gigi is mad short, he must jetpack on Sarah all the time."
"Oh definitely he is mad jetpacking on her."