If you're even remotely familiar with the film This is Spinal Tap, then surely you're conversant about this little legendary piece of dialogue:
Nigel Tufnel: The numbers all go to eleven. Look, right across the board, eleven, eleven, eleven and...
Marty DiBergi: Oh, I see. And most amps go up to ten?
Nigel Tufnel: Exactly.
Marty DiBergi: Does that mean it's louder? Is it any louder?
Nigel Tufnel: Well, it's one louder, isn't it? It's not ten.
But did you know that last November, November 11 to be precise (or 11/11/10), a group of Spinal Tap aficionados started a year-long campaign to make Eleven-Eleven-Eleven "Nigel Tufnel Day" world wide?:
There have been websites and petitions going around on Facebook and other social networks to immortalize the Christopher Guest character (visually inspired by Jeff Beck and behaviorally inspired by 90% of lead guitarists ever) with his own holiday.
There's for example "The Nigel Tufnel Day Appreciation Society and Quilting Bee in Favor of Declaring & Observing November 11, 2011 as Nigel Tufnel Day (in Recognition of Its Maximum Elevenness)" (website here).