When the old jokes stop being funny to you, it’s not that you got boring. You got different.

Your taste moves before you get any announcement about it. Laughing is involuntary, which makes it unusually honest data: when a joke that used to land stops landing, something in what you find true or interesting has already shifted. The temptation is to read that as having gone dull. It is the opposite of dull: you have simply stopped finding the same things sufficient.

So stop producing the laugh you do not have, because everyone can hear it. Go and find material that does land, then bring it back to the group. Half of them are quietly bored of the old set too.