Gryffindor: Can, and will, start singing at top volume. Ends up playing hopscotch a lot.

Ravenclaw: Drafts out an entire story in their head. Or trying to think through something really weird, like time-travel, and giving themselves a headache

Hufflepuff: Talk to anyone around. A n y o n e. I don't care if they're four years old, I'm bored so. People.

Slytherin: Just walks around and pesters whoever's fault it is they're there. Starts muttering under their breath a lot.