The standard ballpoint pen with a cap was the first ballpoint pen many learned to write with in elementary school.

Some of us chewed on the caps or even whistled by blowing into the little hole, which many didn't know had a "life saving" function.

While many of us have dismissed it as "something to do with the ink" – the hole is actually there for a much more important reason.

Zach D, who regularly shares little discoveries he finds interesting, revealed the secret of the tiny hole to his Instagram followers, which the companies that make it are legally required to add to the design.

 

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In the clip, which has more than 3,1 million views, he explained: "Ever wonder why pen caps have those little holes in them?"

– Well, most people think it has something to do with the ink, but the real reason is much more important than that. Companies that make ballpoint pens with caps are actually required to add these little holes. That small hole is large enough to create a flow of air through it in case the cap gets stuck in the throat (trachea) of the person - he says in the video.

Many followers were surprised by his explanation for the existence of that hole and in the comments expressed their delight and surprise at that information.

Some people still don't realize how often those pen caps were in their mouths when they were kids.

- I use it as a little whistle - wrote one follower, while another added that he "remembers how when he was a kid he kept chewing on those pen caps, writes Daily Star.

- Wow, we hope this never happens to anyone - wrote one viewer of the video.

However, others were a little more impressed as they pointed out that not all brands of ballpoint pens have this hole.

- Not all ballpoint pens have this hole - wrote one viewer of the video.