The Posers and Puzzles forum was "spun off" from the General forum as a sort of boffin segregation exercise*. That's fine, in this case though does RHP have enough genuinely funny people to sustain an entire forum?
*may not be true.
Seriously though, why not just keep it to one thread for the time being? By their very nature jokes tend to be "one-stop" affairs, so in an exclusive jokes forum I envisage there being a lot of separate threads with very few posts in them (the joke, and then for the deserving few a "LOL" or two).