More than one occasion student pilots would get their callsigns mixed up and would be told to adopt the callsigns "Stupid 1" and "Stupid 2"
I also remember an irate Sqn Ldr storming into the tower with a huge chunk of ice that had formed on the prop of his Tucano. (causing an engine imbalance and resulting in an emergency recovery) Demanding to know why ATC weren't informing the pilots of icing in the vicinity (it wasn't in the forecast, and the first we knew of it was when he reported it)
Once placated by the supervisor with this explanation, the pilot looked around the tower and then asked "What should I do with this?" cue the Pilot Officer who was ground controller piping up "I can probably find you a gin and tonic to put it in sir!" This resulted in the propeller blade sized hunk of ice being thrown at the ground controller and the pilot storming back out of the tower whilst the people left in the tower descended into fits of giggles