Of course, I probably started it. First day in shop we go over all the safety equipment and rules. The big industrial "Foot operated" sink being very important for cleaning dirt or possible acid spills. Of course there are always those fooling around in the back of the class that usually miss a few things. "Sink? Big deal , wash yer hands."
So a few days into shop a student comes up and tells me there's something wrong with the sink. It wont turn on. I walk over and watch as he shows me how, no mater how he turns the knobs on top of the soap dispenser, the water wont come out.
I walk up, reach over and turn the same soap dispenser "fill" knobs while at the same time stepping on the foot treadle , WATER. "You must be doing it wrong."
Of course other, wiser students, have gathered to watch as he tries a few more times with the mirth of the others.