The world doesn't have trigger warnings. If you get triggered at someone for saying something, if they don't have a tw warning. Just go past it. Don't make a scene. Online or in real life. If you get upset over a joke, you need to ignore it. No ones forcing you to stick around. You can leave and do something else. Online, you can scroll down past it. 

What would happen if you here something trigger you from a stranger? Ignore and walk past or confront them? Make a scene? You don't know if that person went through something. Even you can say something triggering. 

There's not always going to be a warning just for you. 

This is life. I see something the makes me uncomfortable, I look past it and forget it. If it's something serious, get help so you can move past it. 

Sorry if this was bad advice. I just want to rant about something and give my perspective. Examples or better ways of help is helpful.