Unlike the rest of the universe, Joan Rivers isn't all that curious about seeing how big Johnny Carson's penis really is in that sex tape -- because she says ... she's already seen it up close and personal.
Joan -- who guest hosted on Carson's "Tonight Show" for years -- said she and Carson had a "one night bounce" back in the day ... and he was hung like a horse.
Still, Joan says she REALLY wants to see the sex tape for another reason -- check the clip.
See also
Dave Chappelle -- True Pioneer in TV Penis Talk
Dave Chappelle -- Not Impressed by Johnny Carson's Junk
Johnny Carson Sex Tape -- That's NOT an Emmy in His Pocket ... Hiyooooo
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