Green’s Dictionary of Slang

to talk nonsense, to swagger, to boast.

1983		J. Flaherty Tin Wife 200: Puerto Rican thugs on television [...] were being led to arraignment, jive-assing it for the cameras.
1989		R. Miller Profane Men 190: He watches two colored men jive-ass back and forth...saying hello in their endlessly complex handshake [HDAS].