How can the coin pass through the hole?

The coin is passing through a new "apparent" hole created by folding the paper and not through the hole that we see when the paper is unfolded. Right?

Assume a side is 1 unit, a diagonal has length 1.414. then by collapsing the area you might be able to create a slot of 1/2 the perimeter = 2 at most. So the diameter of the coin is d, where: 1.414 < d < 2. And the coin gets through.

Here is an interactive applet which demonstrates why the diagonal fold helps: Try it out at 😉💡🤯

Notice shadow on toy trinket changed allowing the edited paper switch

When you try to put it in one hole and it accidentally ends up in the other hole.

Me trying this trick

Ok, you made me to find my scissors....and it works!!! BTW, it's enough if you fold the paper once, put the coin inside and then press and move the two upper corners one towards the other.

I needed to try myself and it's crazy, but it works. Basically through the folding you are creating a bigger hole, approx. 1.5x the size of the original.

My sofa won't fit thru my door. Will this work?

It's an illusion