My son hid a speaker in the garden under a clump of flowers and every time someone passed he said hello, how are you. We were all watching from the house and most folks just looked around then walked on but when a couple of drunks walked by and started having a conversation with the flowers I thought I was going to die laughing. Naughty yes, but harmless and funny.
I was not quite so amused when said son played a trick on me by saying someone calling himself Fores Kinn had been trying to contact me and I fell for it. Guess you can work out what I was calling over the CB for several seconds before I realised what I was saying..