A professor of mine decided that it would be funny to switch out different sized gloves in the lab.

What was more over the top was that he replaced some of the commonly used reagents with different fruit juice, etc. Needless to say, the students were confused as crap as to why things aren't working.

Luckily it was a small upper division underclassmen class, so it was not detrimental to, say, graduate studies, etc.