peg someone

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
Farlex Dictionary of Idioms.

peg someone

tv. to gossip about someone. Kim is always pegging Jill. What’s her problem?
See also: peg, someone
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • peg (one) as (something)
  • peg (one) for (something)
  • peg as
  • peg (one) down as (something)
  • have (got) (one) pegged as (something)
  • have someone pegged
  • bore into
  • bore into (someone or something)
  • no doubt about it
  • bear in (up)on (one)
References in periodicals archive
It is tough to peg someone as a letdown when he plays a position that generally gives nothing.
Let's truck along and look for catchers