A valve used in chemistry for titrations that controls the flow of a liquid (preferably white). They are prone to leakage and can cause a large, white mess. Cock stoppers are sometimes refereed to as "cocks" for short.
Dude did you see his 'cock was leaking? That will make a mess! Those cock stoppers are so gay!
by shoeman123 June 02, 2011
1. Noun: A girl/boy who stops stroking the meat RIGHT when you are about to cum. This term only applies to a Handjob/Blowjob but only when the orgasm is ruined.
Alex: Hey dan your mom is a cock stopper! She stopped suckin RIGHT when I began to shoot it and it ruined my orgasm.
by Pectabyte August 03, 2006