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
Ulysses	yoo-LIS-eez (English)	Roman Mythology, English
VirgÍLio	-	Portuguese
Davin	DAV-in	English
Marina	mah-REE-nah (Italian, Spanish, German, Russian), mə-REEN-ə (English)	Italian, Spanish, Portuguese, German, Swedish, Norwegian, Danish, Dutch, English, Greek, Russian, Uk
Mu	-	Chinese
Olympe	-	French