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
MihÁLy	MEE-hie	Hungarian
Jodene	JO-deen	English (Rare)
Zipporah	zi-PAWR-ə (English), ZIP-ər-ə (English)	Biblical, Hebrew
Vanesa	-	Czech, Slovak
Vakhtang	-	Georgian
Wioletta	vyaw-LET-tah	Polish