Fake-laughing at a joke you didn’t find funny costs more than it looks like.

One fake laugh is nothing. The cost sits in the accumulation, because each one teaches the room a slightly wrong version of you and teaches you that going along is cheaper than being clear. Do it enough and you end up in a group calibrated to somebody you are not. Then leaving feels dishonest, when the dishonest part happened much earlier.

Watch for the moment your face moves before you decide anything. You do not have to object or explain yourself. Just try the neutral version once, and notice that the room survives it.