To be fair to him he's not he's generally extremely well behaved, he's just sharp as tack and an absolute problem solver.
So you've been told you can't have snacks..so what do you do?..wait until the parent goes to the loo and raid the kitchen after ensuring the toilet door is closed (I used to leave it open when it was me and him so I could keep an ear out...he would come and shut it).
Although the day I was in the shower, he had an accident as we were doing potty training and he got the cordless hoover to clean up a number 2 rather than asking for help was certainly a test.
He follows rules/instructions...but he likes to bend them wherever possible