how about making a deal with farmers. A couple of RasPi or Arduino and some IR detectors. Have them placed near those gigantic industrial chicken coop. their head movement would cut the beam and the timing would generate the data.
Not safe. A clever attacker will hide a kinect in there and figure out your numbers. Nevertheless, it would certainly be the funniest RNG ever invented
Q: Why did the chicken cross the road ?
A: To generate enough entropy.