The smallest things can turn an ordinary photo into a mind-bending optical illusion. That's just what has happened with an innocent-seeming photo of a young girl holding a bag of popcorn that someone posted to Twitter. The girl is standing on a field that's being used as a parking lot, so some of the grass has turned brown from all the cars driving over it. That light brown just happens to be the same color as the popcorn in the bag, so when you look at the pic, the girl seems to have disturbingly thin legs. Even when you know about the bag of popcorn, it's still hard not to see the girl with super-slender legs.
Not surprisingly, there have been plenty of responses to the optical illusion on Twitter.