A joke becomes less harmless when only one person is expected to absorb it gracefully.

Humour is shared when the cost is shared. If one person in the room is always the subject and always required to laugh along, the joke has become a small levy paid by the same individual every time. The group gets the lightness. The target gets a job. Being expected to take it well is part of the arrangement rather than a separate kindness.

Watch where the laughter in your circles lands, and whether it lands repeatedly on one person. If it does, you can change the subject, or say afterwards that you did not find it funny.