In the seventies I worked at a well-known men's wear shop in the Old Town. A friend I worked with was always playing jokes on customers when the boss wasn't around.
We once got caught playing an improvised game of cricket with a ball of paper covered in cello tape. The game ended abruptly with me scoring a six, by the hitting the paper ball passed the boss's right ear as he arrived back from lunch.
One of the favorite tricks was to take the wig off one of the window dummies and wear it, sometimes standing in the window like part of the display, we'd stand still for ages, until someone came to look in the window, then we would suddenly move and frighten the life out of the passer-by.
During windy conditions one-day the top of a Bellsh'a beacon fell off its post on the zebra crossing it rolled into our shop doorway. We phoned the local council who came out to put a new one on but they didn't bother to take the old beacon away, we ended up with it in the shop.
So we carried it upstairs into the top room, three floors up a narrow staircase with very creaky boards. A few days later a huge crowd was gathered outside the shop all craning their necks upwards to the top window, I wondered what was going on, I looked up and in the window was the old Bellsh'a beacon top staring out of window with a big red face in red marker pen drawn on it, smiling away happily.
The crowd was in uproar at my friend's latest joke and they fell about laughing at our schoolboy prank.
The boss told us off when he found out later and we had to take it down.