There’s always a question of how much you should mind your own business. I’m certainly not going to eavesdrop on a stranger’s conversation, pass a judgment, and interject to tell them what I think. I would definitely do those first two things, but the third is crossing a line. 

There’s an art to getting involved in someone else’s personal business. As far as I see it, you should only engage with drama if you’re okay with being the drama sometimes. If you’re willing to be the subject of other people’s gossiping, you can gossip as much as you please. You can’t be a total gossip, and then get angry when people also gossip about you. That’s not how it works. Sometimes, the things you’re doing that elicit gossip from others are for the greater good, and you still have to deal with negative consequences anyway. But often it’s more complicated than that.