a person who chooses to always sleep on the couch rather than their own bed. This person does not sleep on the couch because he/she does not own a bed, but rather in preference for the couch's physical beauty over the bed's internal qualities (i.e. springs, memory foam, or other) and their relationship (proximity of the bed to the couch; this being generally short). Further qualities of this individual is that he/she will sleep on the couch at any time of day not only night; he/she will enjoy quickies (short naps) or extended periods of enjoyment (7-10 hours of sleep).
Shane: "Dude when I woke up this morning for class Mike was sleeping on the couch again!"
Kevin: "Doesn't he have a bed? What a couch slut!"
A couch slut is one who takes up an entire couch forcing others to make two decisions. They can either sit on another close by couch, or they may sit ON the couch slut. Couch sluts generally don't understand what it means to be a couch slut, therefor making the whole situation more humerous.