To be upset or angry, usually when one is put on the spot as
talking out of their ass, or caught in a lie, a classic example would be someone who talked a lot of
trash before a sports game and then gets beaten soundly and is
pissed about it.
Brad bragged to Jim he could
beat anyone in basketball, and talked
trash for days. Jim challenged Brad and
beat him 10-1, at which point Brad stormed off, salty.