Laughing along when someone gets roasted too hard is still a vote.

Laughter is not neutral. A joke that has gone too far needs an audience to keep going, and the people laughing supply it, including the ones who feel uneasy while they do it. From the inside it feels like staying out of things. From where the person standing in the middle is, the room just agreed.

You do not have to make a speech. Going quiet, looking away, changing the subject, or saying the person’s name in an ordinary voice is usually enough to break the rhythm. Try one of those the next time a room tips, and notice how fast it works.