What is "jacking off"

Usage examples of "jacking off".

Boys jacking off in the school toilet know other as agents from Galaxy X, adjourn to a night spot where they sit shabby and por- drinking wine vinegar and eating lemons to the tenor sax, a hip Arab in blue glasses sus- to be Enemy Sender.

It had nothing to do with the memory of seeing Dragon jacking off the night before.

Come on, Eddie thought, what are you doing down there, jacking off?

I could spend three months aboard a ship run by a borderline psycho, or the rest of my life jacking off on the Moon.

All this time in Balanga standing in the pasture and later burying some of the dead I tried to think of my wife and two small daughters, sanity, a home and a bed, her breasts and mouth and lovely hands, but she kept drifting away and I was too numb or unfeeling to care really whether I could bring her back, the sight of her standing naked in a dim room, and on the ground next to me a man I had thought to be dead was jacking off, flat on his back, beating it in a quiet frenzy.