verb. A non-master-of-your-domainy, post-sheep-counting, mega-ishy activity that you had better not be doing in the top bunk, mister.
Real citation: "Someone i used to know used to sleepwank, she'd wake up flicking her bean. very embarrising on guide camp."
(Phil, April 26, 2003, http://www.voodoojunkie.com/voodooboard/viewtopic.php?p=172872&sid=ede3cab70df57a388df05276c29e2d08)
Made-up citation: "I thought snoring and jimmy legs were bad qualities in a bedmate...then I read about sleepwanking. Get me to a nunnery, stat!"