Every single year, Christmas Day creeps up upon us, and many householders will be putting their decorations up this weekend as it'll be December - but there's one red lightbulb people are finding, and they're baffled about it.

As people desperately search through their loft for decorations they've been gathering for years, pulling out lights upon lights from the loft, alongside wreaths, many will be focused on the task at hand so won't really be paying attention. But the more eagle-eyed amongst us have been discovering that on their string of lights, there's a red lightbulb, and it has a surprising purpose, leaving people mind-blown.

Taking to TikTok, a woman explained the little-known use of the small light and her demonstration has amassed millions of views. Many claimed that they believed the small red light to be a spare bulb or a replacement. But the game-changing red light has a proper purpose - and it's fantastic.

The woman shared a demonstration of her putting the light to its intended use. You start by simply removing a single bulb and replacing it with the red one. "Remove regular bulb and replace," the TikToker advised in her demonstration.

The extra light is not only different in colour from the rest, but it also gives the string of lights a flickering effect rather than using a modern-day remote. The woman admitted: "I was today years old when I found out what these are for." Flocking to the comments, viewers shared the surprise in their thousands - with several admitting that they thought it had a different use entirely.

"I thought they were spares", someone admitted, and a second added: "Wait what??????? I thought they were replacements!" A shocked third used wrote: "I swear to god this app has taught me more in the last year than I have been alive."

Meanwhile, a different user commented: "Dude all they had to do was write that somewhere on the box. I wasted so many years not knowing about this." Some even said they were "embarrassed" that they didn't know this.

Meanwhile, other people claimed that they've been aware of the little-known use for decades. One person said: "As someone who grew up in the 90s…I thought everyone knew this - We didn't always have remote control lights!!" A second agreed: "I used to put up the Christmas lights at my parent's house, so I didn't know that this wasn't common knowledge."

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