Instead of getting into a fist fight, there are many ways to make the challenge more civilized.Yang Jwing Ming told a story of a guy walking in and challenging him to a fight once. He was teaching a Long Fist class at the time. He told the guy to take a seat and that he would be with him as soon as class was done. As he worked with his students on various strikes and joint locks the guy sat and watched. However Dr Yang was so busy teaching he did not pay much attention to the guy. When class was over, the guy was gone. Said he saw the guy on the street a couple times after that and all the guy did was say "Hello Master Yang" and keep walking by.
Someone challenged the preying mantis master Brendan Lai. Brendan said, "When I punch you, if you can block my punch, you win, otherwise, you lose". When Brendan said that, Brendan moved his fist toward his opponent's chest. The guy thought Brendan was going to punch toward his chest. When Brendan punched, Brendan punched at his face instead.
Someone challenged SC master David C. K. Lin. David said, "I'll attack you 3 times. If in any of my 3 attacks, you can stand on your feet for more than 3 seconds, you win. Otherwise you lose." In all 3 David's attack, that guy could not stand on his feet for 3 seconds.
In all examples, you try to lead the challenge toward your strong point (such as Brendan's fast punch, and David"s throwing skill). IMO, it's a good strategy.