Henry Rollins does a lot of international travel, both on tours with his band, and for his own edification. On one such tour, their bathroom sink had a little sign over it that said "Be Drinkable".
The correct interpretation was that the water that came out of that tap was potable, or safe to drink. They took it in a more creative way.

In the flavor similar to the annoying "Be Well" signs all over in the movie Demolition Man, they took it to mean "Relax"!

And so, it became sort of an inside joke: "Hey! That guy just hit me!" "Hey, man! Be drinkable!"

...guess you had to have been there...