Death Shredder 

The death shredder is when someone holds their own penis and a second person (usually another male) moves the first person's arm up and down manually, thus "helping" the person masturbate. Since the second person isn't touching the penis directly, it isn't gay.

During the drive to Maryland they got really bored and so Bill gave Jordan a death shredder while I was driving.

Death Shredder by msumaltman September 22, 2009