McDonald's Christmas coffee cup has sent the internet into a frenzy

Forget the frenzy over Starbucks' red holiday cups, now it's McDonald's sending coffee lovers wild - and for a very cheeky reason.

One eagle-eyed McDonald's fan noticed that the design on one of the limited edition festive McCafe cups looks like someone showing off their derriere, if you make one small alteration.

And the NSFW (not safe for work) observation has sent Twitter into a meltdown, with the image going viral on the social media website.

One user compared it to a Turner Prize-nominated sculpture of a man clasping the cheeks of his posterior.

The design on the front of the red cup is supposed to look like a pair of mittens.

But if you draw fingers on the thumb of the mitten, it instead looks like someone clasping the cheeks of their posterior, and mooning the world.

The very rude design was spotted by US fantasy author Sam Sykes, who posted a picture of the cup with fingers drawn onto the design to Twitter yesterday.

Since then, his NSFW observation has had more than 12,000 retweets and nearly 20,000 favourites - and many people say they 'can't unsee' the cheeky logo.

It is unclear in which country the McDonald's mitten cups come from, or if they are even real. The fast food giant has been reached for comment by Femail Food&Drink.

- Daily Mail