What do you do?

Worse is having to make a call down the line in a slowpitch game when the outfield foul lines haven't been marked and you have to use judgement relative to the pole and the infield foul lines. I've called some close ones that guys will stand there and look at it after I've called it and say how the hell was that foul??? I said "see the mowing line?, that's the foul line." Answer from howling monkeys: nothing.