(Update 1 - 10/18/2006)
Something else that never occurred to me before is that there might be more than one Turkey Testicle Festival. Apparently there are at least two others, besides the one I mentioned below. Here's the Web site for another one in Illinois, at the Parkside Pub, in Huntley.
The third such fest has taken place for the last few years in Fort Myers, Florida. According to recent reports, the town council there had expressed some reservations about the propriety of the name, but decided to allow the event to continue as the Turkey Testicle Festival. This one takes place at the Surf Club bar, in Fort Myers, but there doesn't appear to be an accompanying Web site.
(Original Post - 10/08/2006)
It never occurred to me before that turkeys might have testicles, but it's also not a matter that I've ever given much thought.
If you've got nothing to do October 14 and you're in the vicinity of Byron, Illinois, you might want to drop by the 28th Annual incarnation of the Turkey Testicle Festival. Or you might not. All depends on your inclination toward this sort of thing, I reckon.
While you're looking around at the Web site, make sure to check out the Turkey Testicle Song.