Would you see a weak old man and still fight with him? Would an adult see a 3 year old kid and punch him in his face?
All these doesn't makes sense, although rather radical. But yet such people exists...
There is a saying: "Go pick someone your own size"
I will change that, go pick someone who have the same amount of strength that you do...
That's indeed what happened. Someone stronger than me, being a close friend, yet overpowering me when he knows better not to. Would you tolerate such a person? Even if it means that he sees it as a joke? When you are serious about him not to do so?
Same message goes for those who like to pick on others. Go find someone your own build and strength or even stronger and don't take those weaker than you for granted.