Gone bad, but was it good in the first place?

What's the expiration date on a joke? If you come up with something funny to say, and you like that joke yourself, is it okay to use it again when around different people? It's something that always makes me feel a little cheap and that I'm so uncreative that I have to latch on to whatever I can get, but it also seems a shame to throw out a perfectly good joke when it's still fresh and potentially enjoyable. But on the other hand (realizing that I'm at at least three hands by now), there's something that's inspiring about one joke being in one moment for one person or group and then after that, the moment's gone.

Discuss.