PayPay UK has confirmed in a tweet that the Steam Winter Sale will in fact get underway on December 22. That date first came to light at the start of the month by way of a leak on NeoGAF—and which also happens to be the date that last year's winter sale began. Surprise!
What makes the tweet strange is that it doesn't appear in the PayPal UK Twitter feed: It only turns up if you hit it through the link. Click the button and you'll be prompted to fire off an auto-generated tweet trumpeting your insider knowledge, and also revealing the date. My knowledge of Twitter magic isn't sufficient to enable me to figure out how this invisible tweet thing works, but I will say that tweeting things people can't see unless they're emailed the info by a PR agency seems like an odd way to drum up publicity.
On the other hand, Steam Winter Sale 2016 date confirmed. It doesn't have quite the same ring as "Half-Life 3 confirmed," but it's nice to know that we have a few days to prepare our bank accounts for the next exciting round of "I'm probably never going to play this but that is just too damn cheap not to buy." We'll post an official notice of the flag-drop when it happens.