I need a little help

What's the etiquette on guys fighting girls? I know Andy Kaufman didn't have a problem with it. Is it okay to toss a punch back after taking a couple blows. Is it a fair fight where anything goes? Is it still shut up and take it? Can a slap but but not closed fist? Do I have to try and restrain the lady until she calms down?

Don't worry. I'm not going around looking for fights with girls, just old men.