This effect never fails to amaze everyone. I've been doing this for the past several years or more. Only problem is that I lost my Budweiser cap and when I went looking to buy more I couldn't find it. The new Bud bottles don't look like that anymore. The caps are out-dated now. You can't find the Budweiser caps or St. Pauli Girl or Guiness. Unless Alex comes up with newer caps, I wouldn't recommend this trick at all. I'm in Tucson and I can 't find these caps anywhere.