It’s the humor, stupid. Sometimes, it’s the stupid humor.

It’s the acts. The architecture. The confidence cloaked in self-mockery. A title that meant nothing, originally, unknown to Vegas entertainment fans but now the name of the dominant show on the Strip. All of it makes “Absinthe” at Caesars Palace a hit.

The cornerstone of the Spiegelworld empire has turned 12. The show celebrated Monday with a party bitten by dumb luck, a “No Pants” event in the bitter cold. While the brave cavorted in all style of shorts and kilts, attendees were treated to another boffo “Absinthe” performance.

As customary, Spiegelworld founder Ross Mollison turned the event into a happening