Don't bring grandma.
The Underground Rebel Bingo Club started in an old church hall in England when a bunch of drunken friends found a bingo kit. Now it has spread all around Europe and the U.S. The concept is quite the opposite of what you'd expect from a bingo gathering: loud music, tons of alcohol, and people screaming and drawing on each other. Old folks are banned (not sure exactly where they draw the line, but from the photos, it looks like you should be in your 20s or 30s), and fancy or boring clothes are also forbidden. Suffice to say, don't bring grandma.