The joke repeated for strangers may lose the affection that made it harmless among friends.

Words carry only part of a joke; the relationship carries the rest. Among people who know exactly how much you like each other, a sharp remark lands as intimacy, because everyone present can see the affection underneath it. Take the identical sentence to a room of strangers and the affection does not come along, so what arrives is just the sharpness. The teller hears the same joke they always tell and cannot understand why it went wrong.

Before repeating something that works at home, check whether the new audience has the context. If not, tell a different one rather than explaining this one.