Stupid hurts
The universal law of natural consequences. Especially pertains to those whose brains are brand new (children), inebriated adults and retards.
You admonish your children stating that manically jumping up and down on the bed whilst foaming at the mouth is not a good idea but they won't listen. Child eventually flies off bed, proceeds to headbutt the adjacent wall, smashes to the floor winded with a tooth missing. An extended moral lecture is not required just the wry exclamative "Stupid hurts!"