The female version of the "Peter Pan Syndrome"; a grown female who behaves and/or conducts herself immaturely; childish; female that is not accepting to "grow up" and behave her own age; female regression to her childhood.
Some people would say she is having a midlife crisis at age 35 because she loves going to bars every weekend with her 21 year old friends instead of settling down. I suppose she suffers from Hello Kitty Syndrome.
A girl 17 or older who really likes hello kitty and seems cute and innocent, but turns out to be really freaky in bed. (in all good ways of course.)
Bro talk: man, I met this girl who really likes hello kitty man, and I thought she was gonna be pretty regular in bed but dude, I'm telling you. Total freak, and I love it. She's a hello kitty undercover freak!