A radical, who hides his or her beliefs in order to prevent suspicion from any authority figure; an extreme liberal who pretends to be a conservative, usually for gaining money to fund a revolution.
James Cole believed a schizophrenic person was going to release the virus; it turned out a sleeper did the job.
by Vash Westland August 24, 2003

by Cascone September 25, 2008

by Phillip MaCrevice November 29, 2003

A creature, in this case a human, who frats so hard he occasionally (always) falls asleep in whatever frat pose/location he finds himself in.
"Hey check out the sleeper"
"Oh, standard.... Lets take pictures of shit on him, like beer cans, asses, and sorority girls and put them online"
"Oh, standard.... Lets take pictures of shit on him, like beer cans, asses, and sorority girls and put them online"
by Mr. Fletcher June 5, 2013

by Golden Peggy May 14, 2018

(n) Woman who invites herself into your bed, when morning comes does not leave, does not acknowledge subtle hints to leave, makes herself at home. (Editors Note; Sleepers natural evolutionary path is into Bunny Boilers; when one is encountered it is advisable to cease and desist any and all communication while still possible before life and family jewels are still entact)
"Dirk, where are you? Your late, your going to miss the game"
"Sorry, I am having trouble getting this 'Sleeper' out of my house"
"Sorry, I am having trouble getting this 'Sleeper' out of my house"
by Dirk Longfellow June 15, 2006
