peg (one) as (something)
To believe or consider that one definitely is a certain type of person or thing. I pegged her as a total bore when she first started working here, but since getting to know her, she's actually pretty interesting. I'm disappointed, Jake—I never pegged you as a quitter.
See also: peg
tv. to gossip about someone. Kim is always pegging Jill. What’s her problem?