You can actually find videos online of elderly men singing this song, but I have not yet turned up an actual translation, though I think it would come out to something "Guzzle; Splash and Guzzle Again, Splash and Keep On Guzzling", referring to the body's ability to recycle beer over an evening's entertainment.  Writing his message on the front to keep the card legal in the United States, the sender preserved that logo of the Royal Hofbrauhaus, already over 300 years old when the card was mailed