Just take a seat. Walk away. Be quiet. Or simply listen. Because if you don't give a fuck about the topic and you're talking to people who do, then your opinion is neither wanted nor important. There's no reason for you to interrupt or speak or involve yourself in a conversation that, by your own admission, you don't care about. If it doesn't matter to you, don't talk over people who it DOES matter to.
Not all conversations need to involve you.
This also applies to...
"I don't know about/haven't heard..." - basically anything that indicates you're wildly uninformed about the topic (because we all know that you're pulling your opinion out of thin air and are probably about to spout some nonsense that is both theoretically and factually incorrect - because you literally don't know what you're talking about)
"I don't really know what that means/what that is/what y'all are talking about but..." - see above ^
"It's not really my business but..." - pretty self-explanatory
