(I give activity sessions for young children at a small museum in Scotland. During one of the sessions, the children have to guess what a mystery object is – in this case, some tobacco leaves.)

Me: “So you’ve guessed it’s some leaves. Does anybody know what leaves these are? A clue is the smell.”

(The children look nonplussed, understandably.)

Me: “Well, it’s a good thing you don’t know what this is. You’re all a bit young to be allowed this. Any guesses?”

Child: “CRACK!”