whippersnapper (n.)

• boldface
• brat
• chutzpanik
• cipher
• dummy
• elf
• figurehead
• gamin
• hussy
• imp
• jackstraw
• lightweight
• mediocrity
• minx
• nebbish
• nobody
• nonentity
• nothing
• nullity
• obscurity
• pip-squeak
• puck
• punk
• pup
• puppy
• runt
• scrub
• shrimp
• squirt
• squit
• swaggerer
• upstart
• urchin
• zero
• zilch