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
Eadberht	-	Anglo-Saxon
Cynthia	SIN-thee-ə (English)	English, Greek Mythology (Latinized)
Kiarra	-	English (Modern)
Doris	['dɔris]
Gregorius	-	Late Greek (Latinized)
Roxanne	rahk-SAN (English), rok-SAHN (French)	English, French