This is an overgrown teeny-bopper
. This person is college-age(18-24), but still likes many of the things young teens like, such as the Jonas Brothers, Disney Channel, Miley Cyrus, etc.
My sister is such a twenty-bopper. She's 21 years old and went to the midnight showing of Hannah Montana.
People in their twenty's who emulate the younger version known as teeny boppers
. They dress in strange and loud fashion, hang out in awkward places and want so desperately to belong and be cool. The main difference between twenty boppers and teeny boppers
is that twenty boppers are incredibly and unforgivably pretentious. Another name is hipster
I couldn't stand the little group of twenty boppers in front of me at Starbucks.