The Sneaky Gauntlet
When your girl of choice (preferably your girlfriend i suppose...) is in deep sleep you slowly and covertly move her hand into place near the cock, forming her hand into the shape of your hand when thus is preparing for masturbation and proceed to use her hand for pleasure.
"So uhhhh lets get down and dirty tonight honey." "Awwee I'm tired. I think I'm just going to lay down to sleep. Not really in the mood." "Ah...Ok i guess...goodnight..." 45min. later. "Gonna try The Sneaky Gauntlet hope she doesn't wake up...or do I."