That person who has an excuse for anything and everything. No matter what the responsibility needing to be done was, or how easily it could have been done, the Excuser-User will not complete this task. They will simply supply you with some bull-crap excuse for not doing it.
person 1: Hey did you finish that paper?
person 2: Nah, I was too busy.
person 1: You had ten hours to do it last night!
person 2: Well yea, but I went bowling with my friends and then took my dog for a walk and when I got back, CNN was on...
person 1: God, you're such an excuser-user.