To wake up and find you mysteriously have a knackered arm
"ahh shit i must have been sleep wanking all night"
by TMB June 17, 2003
2 more definitions
The act of wanking prior to sleep, so as to improve the quality of your rest and also have an excuse to think of unfuckingbelievably hot chicks.
Griigor: I should have my good sleepwank and a nap.
by AnimusNine April 28, 2009
The art of having a wank whilst sleeping.
"I had an awesome sleepwank last night dude"
by Pik0r June 17, 2007