At what point do you step in and offer help?

I am a bachelor and don't have the wife problems. But, on the farm I work with my brother. He asks to be directed back up or, using the bucket tractor to pick things up. Then when I give him directions he does something else. I sar raise the bucket on the tractor and he will tip it back. I say tip it back and he will raise it up. Then he says "Well I could see that doing it my way would work better." In that case I say "Well do it yourself then". Of course by this time we are no longer talking in a quiet/ normal tone of voice. For years I just took the tractor away from him and let him direct me because I will listen to his directions. But, he is getting to old for the manual labor and wants to drive now. So, I've learned to just calm myself down, walk away, and give up. Better to let him do it himself and get mad at me for not helping then us both getting mad. At least I'm calm and not stressed out and he can get as mad as he wants. No skin off of my nose.

(Other people have watched us do this and for some reasons they always seem to think it's funny. The more mad at each other we get the more they laugh. I don't get that part I guess).