Know-It-All was one of the nicer things people used to say to me. If it was an area of interest to me, then yes, I tended to talk on & on about things like insects, dinosaurs, snakes, space until the other person started begging for mercy. Ok, that is a bit dramatic.
The label certainly fit, though I knew much less about sports & other stuff than my peers.
I was also called 'Professor" ( from Gilligan's Island) frequently.
Matthew