Although often referred to as a side effect of blowing one's load, this is also an acceptable term for someone who is stupid, lame, a douche bag, or simply a raging tool whom you feel utter disdain for.
Hey, cumstain, why the hell did you eat my sandwich?
1. A dude who goes to a bar/restaurant/venue and while his other friends toss in their lines trying to catch some trout (see vagina), he starts talking to guys and puts forth no effort in getting women back to the house.
2. A dude who runs around at night with a burglar mask and burlap sack stealing all the cocks (see penis) in the neighborhood to add to his collection he displays on his mantle.
What the hell, Ted, why you such a cock collector?