Sun, sea and XXX: Holiday advert becomes massive online hit because of VERY rude optical illusion (3 Pics)

A Dutch holiday advert has gone viral due to a rather unfortunate optical illusion.

Neckermann, Thomas Cook's sister company operating in mainland Europe, recently released a marketing poster in promoting 2-for-1 holiday deals.

But a picture for the German company's campaign in the Netherlands appears rather X-rated at first glance.

 Neckermann's advert promoting 2 for 1 holiday deals has gone viral due to an unfortunate optical illusion

Due to the unfortunate placement of a man's hand and leg, he appears to be pleasuring a woman sat on a sun lounger.

Actually, he is simply cupping his own knee while the woman sunbathes beside him.

The optical illusion left many people online in hysterics after the advert was posted widely on social media.

'And you get a free one too!' one joked.

 Thomas Cook's recent gaffe came after the company had their planes repainted to say 'I Love Cook's Club 

The placement of the letters on the livery means an embarrassing phrase is spelled out when the doors are open

'It's the expression on the people's faces that makes you second guess yourself,' noted one user.

But some users cynically noted that Neckermann may have intended for the advert to go viral.

'They knew what they were doing,' said .

Another added: 'It made me do a double take so they're doing something right.'

It comes after Thomas Cook's recent gaffe after the company had their planes repainted to say 'I Love Cook's Club.'

But they discovered the placement of the letters means an embarrassing phrase is spelled out when the doors are open.