This cheeky photo went viral for one obvious reason. Can you see it? Photo / Facebook
It's time to test your eyesight.
Take a look back at some of the year's trickiest optical illusions that went viral online and stumped us all (well, most of us).
At first glance all seems to be normal in the image below, but then it seems there are legs, butts and arms all over the place. Which bit belongs to which person?
As commenters eventually figured out, the illusion springs from the design on the man's shorts. Wait for it...
Instagram user Hunter first posted the image below online in September before it was reposted by Twitter user @kingkayden and retweeted by thousands of users.
He asked the simple question: "Are these legs shiny and oily or are they legs with white paint on them?"
They ended up covered in paint, can you see it now?
In April, a British Twitter user shared a confounding video of his son's toy train tracks, which appeared to show one track growing and shrinking depending on where he placed it.
This is called the Jastrow illusion and has to do with the way the brain interprets curved segments.
The following image was uploaded to Facebook by Arron Bevin, and really does look like some strange unidentifiable object.... BUT WHAT IS IT?
The image went viral as people have spotted a hidden optical illusion of something emerging from the wall - a cigar.
Russian artist Ilja Klemencov has hidden a giant panda amongst black and white zig-zag lines.
While the mammal instantly jumps out at some observers, those who are struggling to see it are advised to take a step back from their computer screens or turn it to a near 90 degree angle.
When you look at this red dot, what do you see? If your eyesight is good enough you'll note a picture hidden inside the circle.
Given the option to flip the image, the overturned dot reveals a detailed sketch of a horse with a mane, tail, saddle and bridle.
In July, a Facebook user in the Philippines posted a photo of a floral carpet and challenged viewers to find the camouflaged phone placed on it.
These were followed by other "spot the thing" illusions that became viral this year.
One illusion that divided puzzle fans features a mystery lake - or a wall?
According to Playbuzz, what looks like a lake is actually a light-coloured wall, and the white "shoreline" is the light catching the top of the structure.
Two animals are pictured in this image below - what's the first one you see?
- Daily Mail, Washington Post, news.com.au, nzherald.co.nz
The new free open-air saltwater pool is already proving popular.