godan verb (-ru)
act like a know-it-all; pretend to be an expert
Colloquial, often derogatory. Describes someone who puts on airs of being knowledgeable or 'in the know', especially about a specific topic. Related to 通 (つう) meaning 'connoisseur' or 'expert'.
See also: 通がる
彼はいつもワインに通ぶって、難しい用語を並べる。
He always acts like a wine connoisseur, throwing around difficult terms.
そんなに通ぶらなくてもいいじゃないか。
You don't have to act like such a know-it-all.