Every so often an image pops online and sends everyone into a frenzy.

We've been already been subjected to mind-bending images of a color-changing dress, strawberry cake and more recently the case of the "couch-centaur."

This week, another image started floating around the internet it has made some people very confused.

The photo appears to be a seemingly snap of a group of young people on a night out but when you take a closer look, something seems to be off.

Do you see it? The girl with the strawberry blonde hair standing beside the guy seems to have an abnormally long arm.

Eleanor Bailey shared the picture of her sister's extra long arm on twitter after she noticed the odd but hilarious optical illusion.

"As soon as I saw the photo, I knew people would like it," she told  Huffpost.

If you still haven't figured out yet, here's how the illusion works: The girl and guy beside Eleanor's sister are both wearing black which makes it appear as though her arm extended all the way out.

Take a look:

Did it take you long to figure it out? Let us know in the comments!