When I first uploaded my current icon I noticed it had a punch of jaggies, so I slightly blurred the image, saved it to a new name and uploaded the new file. In gimp the two versions look very different but after I upload them they look identical, like the image was further compressed and that returned the jaggies as a compression artifact.
Anyway, I got it from here:
It looked like Rev. Bob Dobbs (Church of the Sub Genius), so I grabbed it.