smart aleck (n.)

• blowhard
• boaster
• boldface
• braggadocio
• braggart
• chutzpanik
• egocentric
• egoist
• egotist
• exhibitionist
• gasbag
• grandstander
• hussy
• individualist
• know-it-all
• minx
• narcissist
• narcist
• pup
• puppy
• show-off
• swaggerer
• swellhead
• upstart
• whippersnapper
• windbag
• wiseacre
• wisenheimer