ha ha! havnt heard that one,but i have heard the ration pack lesson!
Everyones rat pack would be tampered with,a sachel with 2 x tic tacs were added.
The instructor would then demonstrate how to boil a cup of water,adding the tic tacs as (de-hydrated boiled eggs!)
While the water was boiling,another instrutor would demonstrate how to cook something else,like a can of whatever. The cup with the tic tacs was replaced by one with real boiled eggs, and the inst,would say something along the lines of,"lets see how the eggs are going,ah perfect!"
The recuits were then sent away to cook up their meal....there would always be couple who fell for the egg gag,and say something like "CPL,my eggs dont work!" and be sent away to try again,or told off for not paying attention! Very funny if done right!