Green’s Dictionary of Slang

1. (US) smart, well-dressed.

1945		S.J. Perelman letter 26 Mar. in Crowther Don’t Tread on Me (1987) 61: I have become a whippy, probably homosexual youth reminiscent of Dorian Gray in his earlier phase but far more handsome.
1968–70		Current Sl. III–IV (Cumulation Issue).
1979		E. Torres After Hours 166: Damn, Carlito, you still out there lookin’ whippy.

2. cheeky, mocking.

1963

M. Braly Shake Him Till He Rattles (1964) 56: When you get all through being whippy, will you answer my question?

3. (US campus) intelligent, clever.

1969

Current Sl. III:3.