adult-tard
An adult who does ridiculosly stupid things as a way of showing their maturity. Eg; when a little bird finds it's way into a classroom of fifth graders, and adult-tard would be the first one to catch it and call animal protection, instead of letting it fly away. Making oddly stupid rules and descisions is another habit of adult-tards.
At my school, they caught someone smoking in a restroom stall and the adult-tard principle made a rule against using the bathroom. 
(true adult-tard moment)