Having a quiet Sunday in the tower at Manston many moons ago when I get a call from an instructor at Biggin Hill telling me he has a student doing a cross country and would like to do a few circuits and some emergency procedures. After clearing it with the Satco it is agreed and two hours later the said C152 arrives and starts bashing the circuit.
Turning crosswind after a go around the he transmits "PRACTICE MAYDAY, PRACTICE MAYDAY, PRACTICE MAYDAY - simulated engine failure."
Ten seconds later the squawk box from the Coastguard SAR opens up (they are monitoring the frequency) and a resigned voice says, "tell him we can do a practice scramble if he will pay for the fuel".