Why is there a "33" on the back of a Rolling Rock beer bottle?

Dear Matthew Alice:

On the back of the Rolling Rock beer bottle (brewed by Latrobe Brewing Co.) there is a "33." Me and my friends have been curious for many years about why it is there and what it means. We have tried calling their customer service number, but they would not give us any info, except that they are as ignorant as us (or are pretending to be). Help us solve the mystery.

-- Sara Burgin, San Diego

Forget it. You don't know; they don't know; I don't know; nobody knows. But all beer drinkers wonder. Latrobe turns bad record-keeping into ongoing publicity. The number's been on the label from the start (1939). If it meant something back then, nobody at the company now remembers. Common guesses: the number of words in the beer's "pledge"; number of letters in the ingredient list; the year Prohibition ended. Some say it was a typesetting glitch and means nothing.