I think anyone who has had a fight and who's a very good observer of the situation and people's behavior is capable of writing a fight. But you do start thinking about writing during the fights that you have with your partner.
When they saw me walking down the street smoking a cigar, they'd say, 'Hey, that 14-year-old kid may be going places. ' Of course it's also a good prop on the stage. . . When you can't think of what you're supposed to say next, you can puff on your cigar until you think of your next line.