Saying “that’s not funny” when everyone’s laughing takes more nerve than any dare.

Groups run on momentum, and interrupting one is harder than any single conversation because you are not disagreeing with a person, you are stepping out of a current. Everybody laughing feels like consensus even when half of them are uncomfortable. The nerve it takes is the same nerve required to be the first person to stop.

You do not need a speech. Four words and a shrug, then let it be awkward for a second. The ones who were uneasy will find you afterward, and next time one of them goes first instead.