Incredibly rude optical illusion shows whether you have a filthy mind… can you spot the X-rated image?

A FESTIVAL reveller appears to put on a cheeky display in this surprising optical illusion.

Some reckon how you see this image could be a sign of a filthy mind - because there's an innocent explanation.

The image was posted on Reddit under the title "Confident lady at festival".

In front of the couple holding hands, your eye is drawn to the woman lying on her front on the grass.

Viewers online could hardly believe their eyes.

One said: "Thought it was really an over confident women with a g-string bathing suit on till I zoomed in."

Another said: "That one is next level, it took me a solid ten seconds to manage to not see a thicc a**."

And another said: "I knew it wasn't her a** but it took me a minute to figure out what it actually was."

But some could not work it out, with one pleading: "Can someone help me?"

Another said: "Even after realising what I'm looking at, I'm still confused."

The amusing double image impressed Redditors.

One admirer said: "This is one of the best I’ve ever seen. I can switch back and forth easily."

Another said: "Stuff like this is the only reason I enjoy the internet."

Still can't work it out?

A clue to the perspective trick comes from the rucksack, which belongs to a man who is wearing shorts and sitting in a camping chair.

His hand is resting over his leg, appearing to make an X-rated shape together with his knee.

In March, another illusion left viewers wondering if they were the only ones with dirty minds.

It appeared to some Redditors like an image of a naked couple locked in an X-rated embrace.

In fact it showed a man's shapely legs crossed at the ankle.

Meanwhile a clever stick cartoon is claimed to reveal if you are obsessed with sex.

If you enjoyed that, we've rounded up some more entirely innocent pics that seem filthy at first glance.