I saw this happen with 2 people whose desks were facing each other. The one a-hole moved her stuff over-over-over, I guess because she was an important management intern, until it was on the other person's desk. That person, in turn, instead of just pushing back at opportune times, BLEW UP. Made the few days of conflict kinda worth going to work to see.
If it wound up on my desk and I didn't want it I would throw it out. Solves the problem.