The Daily Beast: In the 1920s, Chaim Soutine riffed on Rembrandt's butchery.
Warhol and Lichtenstein riffed on product logos and comic books because it was ironic.
"melodic phrase in jazz," 1935 (but said to have been used by musicians since c.1917), of uncertain origin, perhaps a shortened form of riffle, or altered from refrain. The verb is attested from 1942, from the noun. Also in extended use. Related: Riffed; riffing.
[1953+; fr reduction in force]
[origin unknown; perhaps echoic; perhaps fr refrain; perhaps fr riffle or ripple in the sense of ''try, shot, crack'']
A refrigerator car; reefer1 (1950s+ Railroad)