Here is a pun about Jehovah’s Witnesses knocking on doors:

Why did the Jehovah’s Witness knock on the door twice?

Because they wanted to make sure they weren’t interrupting the rapture.

This pun is funny because it plays on the stereotype that Jehovah’s Witnesses are always knocking on doors. It also plays on the Christian belief in the rapture, which is the belief that Christians will be taken up to heaven before the end of the world. The pun is funny because it suggests that the Jehovah’s Witness was knocking on the door to see if the people inside were already gone.