Peter Pan
From The Big Bang Theory Wiki
Fictional magical boy from the books and play by J.M. Barrie. Peter is an orphan boy who refuses to grow and instead spends his eternal youth on a magical island called Neverland.
Howard went to Penny's Halloween party dressed as Robin Hood, but everyone thought the costume made him look more like Peter Pan. Raj even commented that he'd seen Cathy Rigby playing Peter and her costume was the same as the one Howard was wearing ("She was a little bigger than you, but it's basically the same look, man.") Howard was annoyed, but eventually just went with it ("I got a handful of pixie dust with your name on it.")