The you-should-have-been-there joke

Yep. The one where your friends recount a so-called hilariously funny incident, laugh throughout the narration, and you are left wondering if you should snicker in support or do the fake laugh. Then there's awkward one which is really the funny part for third party observers: all of you stare at each other before the someone admits that "you really should have been there".

Thinking back, it's not really a "joke" now is it?