Ninjerk
The act masturbating in a stealthy or hidden manner in a public setting; so as not to be seen during the act or moment of ejaculation.
"Dude traffic was hella bad on my way to work, and the chick on the radio had me feelin' some type of wayyyyyyyy. Had to bust out a quick lil Ninjerk in my car so I could concentrate on making this paper."
Ninjerk
Ejaculating before achieving full wood.
Tried to ninjerk before work this morning but it's hard.