I've never before heard of any connection with The Who's Keith Moon, whose name in this respect, I'd guess, is just a 'happy' coincidence. I believe the band first visited America in 1967 and we know the word first appeared in print there in 1968. Would just one year have been long enough for his antics to become part of American English, especially given that these things usually hang about in speech for ages before they're ever written down? I doubt it and will stick with the "large, round, white object" source myself. Cheers.