I Googled both words and it turns out Zug is a place in Switzerland. Ziggerty is all over the board, so to speak; it's everything from a cookie (Hot Ziggerty Bars) to, apparently, a rock climb in Britain, but I can't figure out what it means, if anything. Sounds like it might be a nonsense word along the lines of Hot Diggety! Bradbury didn't come up in connection with either term.