Ironic Delays

I was told a joke that made me laugh once without delay.  A joke that I must tell all who will listen.  And they laughed.  Once.

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I was told a bad joke and it was awful.  No laughs, none at all.  Later it's in my head and wont go away, and I laugh.  A bad joke that makes me laugh every time.  A joke and laugh I can't share.