a wise guy
1. One who is sarcastic or makes jokes in an attempt to seem witty, usually to others' annoyance; a smart aleck. Joe is such a wise guy that it's hard to know when he's being serious. Every class seems to have one disruptive wise guy.
2. A mobster. I wouldn't bother those shady characters sitting in the corner booth—they're all wise guys.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a ˈwise guy(informal, disapproving, especially American English) a man who speaks or behaves as if he knows much more than other people: OK, wise guy, what do you think we should do then?
Farlex Partner Idioms Dictionary © Farlex 2017