The Boston Beer Company advertises quite a bit on a radio station that I listen to. The ads are usually voiced by the company's founder, Jim Koch (pronounced "Cook"), and in many of the ads, he says that Samuel Adams beer has "a head so thick you can float a bottle cap on it." (You can hear one of the ads here.) I've never doubted the veracity of the claim, but the thought occurred to me that you could probably float a bottle cap on the heads of other beers. So I decided to find out, and the results may surprise you...