Green’s Dictionary of Slang

1. (US) a joke, a trick, an act of teasing.

1938		W. Winchell On Broadway 28 Nov. [synd. col.] Club 18, where the clowns ‘louse up’ anybody. The bigger the shot, the bigger the rib.
1946		J.E. Dadswell Hey, Sucker 103: A ‘rib’ is what normal folks call ‘a dirty dig’.
1953		R. Chandler Long Good-Bye 242: Must have been some kind of a rib. Only Magoon ain’t feeling funny, what with both arms in casts.
1963		M. Braly Shake Him Till He Rattles (1964) 136: Is this some kind of a rib?
2012		H. Acosta ‘Doing the Job’ in ThugLit Dec. [ebook] ‘It started as just another rib, a joke to pass the time, but—’.

2. (US Und.) an act of setting up an innocent person.

1926

‘Und. and Its Vernacular’ in Clues mag. 158—62: rib Frame up.