Green’s Dictionary of Slang

pertaining to a teenager, usu. a girl.

1968		T. Wolfe Electric Kool-Aid Acid Test (1969) 208: They start piling round the bus, these little teeny freaks, and start pelting it with jelly beans.
1970		T. Southern Blue Movie (1974) 18: I wouldn’t mind some of that teeny head.
2004		Guardian 31 Aug. 6: The drain on his resources has led the frustrated police chief to call for the ‘teeny discos’ to be shut down.
2009		P. Temple Truth 277: There was a teenie hooker in Darwin, they said it looked like her.