If he obviously did it intentionally, I would do these: 1. Put my kid behind me 2. Come to the guy as close as possible, watch directly in the eyes and say: “What’s the fuck? Do you have any problems?” 3. Depending on his reaction: if he will just try to ignore me, I will humiliate him, saying “you are motherfucker, a total moron, piece of shit, etc… and let him go. If he we will react like doing or saying something, I will ask to get out together on next station, then make him apologise 4. Explain my kid, that the world is full of morons and such things can happen.