The (revised) rules are as follows:
1. The challenge begins at 12:01am local time on the day after Thanksgiving – this year that's tonight, November 23rd. It ends at 12:01am local time on December 24th.
2. If you hear even a tiny snatch of TLDB at any time during that period, and it's recognizable as such, the game's over until next year. Thanks for playing.
3. There are three exceptions to Rule #2.
3a. The first exception is that if someone deliberately plays TLDB just to make you lose, it doesn't count (this, I'm sorry to say, is known as the My Sister Jane Exception).4. (Based on the 2013 ruling by the Commissioner.) Since the date of Thanksgiving floats, scoring is based on how many days remain until Christmas, not how many days have passed since Thanksgiving. So, e.g., December 15th from any year always beats December 14th from any year.
3b. The second exception is that the early 1970s cover of TLDB by Bing Crosby and David Bowie doesn't end the game. I treasure it for its transcendental weirdness.
3c. (Added by the Commissioner in 2017) The third exception is this scene from Tne West Wing. If you happen to see or hear this specific scene, it doesn't end the game. (And yes, if you've ever been to a burial with an honor guard, you'll already know: even if you're braced and prepared, those rifles feel really loud.)
(Note that Rule #4 will mean that this year has a slightly higher degree of difficulty than usual, since in 2017 Thanksgiving falls on one of the earliest calendar dates possible.)
Chances are better for those who do not work in retail, who do their holiday shopping online rather than in stores, and who do not spend time in cars with the radio tuned to all-Christmas channels. Beyond that, you're on your own
Last year, I made it to December 23rd -- a decent, but hardly record-breaking score.
The precise origins of The Annual "The Little Drummer Boy" Competition are lost to antiquity and legend, but many reputable historians of the sport believe it may trace back to this moment on December 18, 1963.
You can read more about my war with "The Little Drummer Boy," and relive highlights from previous seasons-- including the crucial importance of Rule 3b -- here.
If you played last winter, I hope you'll play again this season. If you're a beginner, I hope you'll join. Feel free to check in via the comments here, or at my Facebook Page, to let me know how you're going.
May the odds be ever with you.