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
Wekesa	-	Eastern African, Luhya
Lughaidh	LOO-ee	Irish, Irish Mythology
Zinat	-	Arabic, Persian
Aby	['eibi]
Dobson	['dɔbsn]
Sasha	-	Russian, Ukrainian, English, French