Am I the only one whose kid keeps messing with the thermostat settings?

My son thinks it's a game to turn the heat up to 80 in winter because he likes it TOASTY. I came home to a system running non-stop and a HUGE energy bill. Teaching him basic thermostat respect is now part of my parenting, but man, it's a battle. Maybe we need LOCKING covers standard in every home with curious kids.