A common hobby:

cuticle picking. 

Who isn't guilty?

Just a silent minute, here or there, with nothing of use to do. 

Perhaps it's between games in gym, or when the lunchroom is all but empty.

Either way, I'm sure that my Civics class, at the very least, all have clean cuticles. In case you needed any cuticle-clean people, you've got at least 30 for the job.

Just curious: how many people inspect a persons cuticles to judge them? I'd say only a few, if any. But why then do we spend so much time picking them?

Yet another mystery of the universe.