Comedian David Williams has 'scared' his social media followers by posting a face-swap photo with fellow Britain's Got Talent judge Simon Cowell - freaky!

In scenes due to air on this weekend's Britain's Got Talent, the 57-year-old mogul is left confused by the phone app when presenter Stephen Mulhern puts it to use.

Posing with fellow judge David Walliams, Simon Cowell is left baffled when he is shown an image of himself with his and David’s faces swapped.

"You now can see what you would look like if you had David’s head and your face," an excited Mulhern says.

But Cowell is left utterly confused by the bizarre photo saying: "I don’t understand".

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Little Britain star Walliams posted the snap with Cowell on Instagram and Twitter which led to a flurry of comments from their followers.

Presenter Lisa Snowdon commented, "Now that is freaky," while another fan declared "Creepy, but it works."

While the picture shows the pair sporting each other's glasses and main facial features, the picture app allowed Cowell to keep his glistening white teeth.

Pointing out the dental difference, actress Sheridan Smith asked Williams: "Why do (you) still not have the flashy teeth?"

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Britain's Got Talent, TV3, Saturday, 8.00pm