Besides
http://www.adultfriendfinder.com there is also
http://www.alt.com (related site). I just did a search for Men seeking a Group for Watching only, to do or try Masturbation in my zip code and came up with several results. Also, if you go to
http://groups.yahoo.com there are a few groups on there, too. I do know that it's not difficult to find a circle in NY, but it is not uncommon for the groups to be elitist or mostly gay. Not that that matters since interaction between men as far as I've gathered is pretty uncommon during circle jerks. Anyways, a few internet searches or asking some friends you're comfortable with and you'll probably find or create a group in no time.
And circle jerks don't make you gay!!
P.S. I know for a fact that some circle jerks allow women to join, too. Not that common, though.
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The post immediately below strikes me as hot for some reason.