CALJIC No. 5.50, Self-Defense—Assailed Person Need Not Retreat: A person threatened with an attack that justifies the exercise of the right of self-defense need not retreat. In the exercise of [his] . . . right of self-defense a person may stand [his] . . . ground and defend [himself] . . . by the use of all force and means which would appear to be necessary to a reasonable person in a similar situation and with similar knowledge; and a person may pursue [his] . . . assailant until [he] . . . has secured [himself] . . . from danger if that course likewise appears reasonably necessary. This law applies even though the assailed person might more easily have gained safety by flight or by withdrawing from the scene.
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Part of verbal challenge is to let others in the vicinity know that you are on the verge of being forced into a physical altercation...
Then, when you eventually have to hit him, take him down, whatever, people around will know who's the good guy, who's the bad guy, exactly what's happening, and possibly back you up...
Much better than that they hear a noise, turn around and there you are manhandling an innocent patron (for all they know)!
That being said, it's not so wise to get involved in barfights. especially if it's because you've been out drinking that evening, and followed a new girl to the wrong bar where that dude hangs out regularly with all of his homies...