I didn't believe you guys but you were right....My stool came out green albeit very dark and there were some of it which was brown however. I don't remember this ever happening with regular whoppers, so I guess there is something odd about the bun they're using for this Halloween Whopper.
As for the burger, the one which was made for me was quite terrible. The bun didn't taste too fresh, my burger didn't have much A1 sauce in it, and also the burger itself was lukewarm. Somehow all of this happened when I went there at 1:05pm, which is essentially lunchtime. Shouldn't everything be pretty fresh at that part of the day? Also, my side order of onion rings weren't made. They just gave me fries instead, which I don't like since I don't like BK fries. I can understand that the place was busy but I don't know how come my burger's bun was so crappy.