If there is one thing Adam hates, it's hair. Any type of hair really, accumulating in any environment, produces revulsion. He has trained his fiancee to remove the hair from the shower drain after each use. He also hates that the floors in the lab don't really get cleaned, leaving dust bunny hairball tumbleweeds. We (Jen and myself) were removing gray hairs from another graduate student's head (Jess). We put them on the black bench top to just make sure they were grays because as scientists, we need validation. So here we had a some gray hairs, freshly plucked, and ready for mischief. Knowing how much Adam hates hair we decided it would be really sweet of us to cut these long grays into smaller pieces and curl them slightly, putting them in the middle of his pristine workspace. You can imagine what they looked like, but if not there is a picture provided on the left. We put them in a pile here just for mass effect; we later spread them out to make them less conspicuous. I also put one on his scissors to make him throw up a little bit in his mouth. Look closely and you can see the hair on the handle of those blue beauties.
He hasn't come in to work yet, but I will update when I know the status of the operation.
update: He didn't even notice. That just makes me angry enough to start planting things around his workspace until he goes insane.