a wise guy

(American & Australian informal) also a wise-ass (American very informal!)

someone who is always trying to seem more clever than everyone else in a way that is annoying Okay, wise guy, if you're so damned smart, you can tell everyone how it's done! He's just some wise-ass who thinks he knows all the answers. (American & Australian informal)

See an old head on young shoulders

Common Names:

Name	Pronounced	Usage
Benigno	-	Italian, Spanish, Portuguese
Gordan	GOR-dahn (Serbian, Croatian)	Serbian, Croatian, Macedonian
Reshmi	-	Indian, Hindi, Bengali
Nur	NOOR (Arabic)	Arabic, Turkish, Urdu, Uyghur, Indonesian, Malay
Sergio	SER-jo (Italian), SER-khyo (Spanish)	Italian, Spanish
Timotheos	-	Ancient Greek, Biblical Greek