We're almost 99% sure that we don't actually know how anything works after another video has gone viral for revealing the 'real' purpose of a product we use everyday.
This time it's the turn of the toothbrush - and it turns out those bright colours on them aren't actually just to brighten up brushing your teeth.
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A teacher shared the discovery on her TikTok and explained that the bristles help to measure out how much toothpaste you should be using, reports Daily Star.
Since being posted, the video has racked up more than 4,700 likes and dozens of comments from viewers who were only just finding out the truth.
In the video that has gone viral, with more than 36,000 views, Jess, who lives in Ontario, Canada, showcased the dental tool to her viewers.
She asked: "Do you ever wonder why your toothbrush has different colours?
"There's a reason for that. The smallest of the colours - usually near the top, is to show you how much toothpaste you actually should be using.
"You're actually not supposed to put the toothpaste all along the brush."
Jess then points out the dark blue section of her toothbrush and says: "You should do use about a pea-size amount of toothpaste on the dark blue section here."
Children's toothbrushes also have a similar feature, she said, but the colour patch might be in at the centre rather than at the top of the brush.
One person said "Mind blown. I was today years old", while another adde "No!! Never knew that."
A third commented: "So I've used 10,000% more toothpaste that I needed all my life?"
