One of our physics teachers was called Humphrey Payne, and for some reason, his Christian name became a source of enormous amusement for the whole school. In one physics lesson, determined to irritate Humphrey, Sean Reuben put his hand up and said "Can I tell a joke sir?" and then proceeded to tell a joke which began with the feed line: "What do you call a camel with three humps?". Payne, incensed, turned a bright shade of red and ordered Sean to get out of the class. Sean feigned innocence beautifully, looking as if butter wouldn't melt in his mouth so Payne chased him madly out of the room. Once Sean was outside, Humphrey slammed the door so hard that the security glass in the door shattered. The rest of the class at this point sat in shocked silence.
We erupted into uncontrollable laughter when Sean popped his round the door a few seconds later and with a look of angelic innocence and supposed helpfulness on his face, pointed out to Humphrey, "Sir, I think the glass in the door just broke."