I did not downvote you, but unfortunately you trivialize Popper by invoking his paradox of intolerance in such context.
Popper lived in a world where democracy was threatened by very powerful totalitarian movements and its demise in Europe at least was a very credible scenario. His paradox of tolerance addresses those violent, brutal movements that left a trail of blood and destruction on the continent.
There is zero evidence that Popper intended to micropolice or censor uncouth / rude verbal or written interactions among people. He was mostly concerned about outright tyranny and genocide. And there is a long way from bad jokes to tyranny and genocide, even though the Anglo-Saxon world has evolved a rather thin skin in the last decades and seems to think otherwise.
Making sexist jokes on a mailing list should probably be rebuked or punished by moderators for being in bad taste, but not because of Popper's ideas. A person joking about some girls age almost certainly does not want to enslave/kill women and does not have to be forcibly prevented from doing so.