Choke

Choke is a verb that describes one who runs out of rapped lines too quickly, either by forgetting prepared bars or failing to freestyle fluidly; it is arguably the most incriminating misstep in rap delivery.

For example, from the first scene of 8 Mile, where B-Rabbit gets told to choke out of the battle by the crowd, meaning that "choke" is used instead of "give up" nor "quit".