wise guy 
noun informal
1chiefly North American A person who makes sarcastic or cheeky remarks to demonstrate their cleverness: four years ago the wise guys, the pundits, and the pollsters were all ready to write the president off...
- Some wise guy had a tape measure with him and took a reading.
- Well, I have felt he's been a wise guy for some time and it certainly appears he's being that way now with his interlocutors.
- He continued to play numerous characters alternating between lead and supporting roles in various comedy flicks usually seen as a loveable slob, a bumbling schemer or an overbearing wise guy.
2US A member of the Mafia: he was the boss of the biggest crime family in the country—300 wise guys...
- Could be any inner-city gang member or wise guy.
- In my mind, I pictured him to be a little Italian wise guy, like the mafia hit man that's always the squealer on someone in those old movies.
- While other kids were flipping burgers, he was hiring himself out to local wise guys as muscle or masterminding his own bizarre capers.