To smile at the jest which plants a thorn in another’s breast is to become a principal in the mischief.

Laughing at a cruel joke is not a neutral act. The laugh is what the joke was for, and supplying it makes you part of the thing rather than a bystander to it. Cruelty performed to an unresponsive room dies quickly, while cruelty that gets a reaction gets repeated. You may not have chosen the words, but you paid for them.

When something lands at another person’s expense this week, let the silence happen. You do not have to lecture anyone, and a flat face is usually enough to end it.