33 was the cipher for Sir Fancis Bacon. the architect of the colonization of America. The German Piets colonized in Lancaster county,far from the brew however. the 33 was an indicator the Order of the Quest or otherwise the Order of the secret Philosophers could have a hidden hand in this. The 33 was a symbolic colophon. Just a far fetched theory, but definitely the most fun.
Welcome to the Straight Dope Message Boards, davecirig, glad to have you with us. It’s helpful to other readers (saves search time, keeps us all on the same page) if you provide a link to the column in question, when you start a thread. in this case: http://www.straightdope.com/columns/read/389/why-is-there-a-33-on-rolling-rock-beer-labels
No biggie, you’ll know for next time, and, as I say, welcome.