OK, Ladies & gentlemen...according to an e-mail I received...a 'Tot' is a unit of volume for liquor. Generally the term is used informally, with no fixed definition. However, in British pubs the usual understanding is that a tot is 1/6 gill; this is equivalent to 5/6 Imperial fluid ounce or about 23.7 milliliters. A gill is 1/4 pint, or 1/2 cup or 4 U.S. fluid ounces & 5 British ounces.
Sooooo, a Tot is a tad less than an ounce. And we all know how much a 'tad' is. Right???
I like rescuedad's guess of the measure. A GALLON!! Hopefully he will invite all of us to his house for drinks. Whoo-Hoo!