Hold up before you click. Those “look now” posts are everywhere, with wild claims about Sarah Palin in a tiny bikini that supposedly leaves nothing to the imagination.

Stay with me to the very end, because I’ll show you a fast, five-second test to spot fake photos—and I’ll reveal the one background clue that gives most viral images away. This will save you from falling for clickbait again. Here’s the truth first: for years, edited images have been pushed online to make people think they’re seeing something shocking. The most famous example is the image of Palin in a stars-and-stripes bikini holding a gun. That photo is not real.

Fact-checkers confirmed long ago that her face was pasted onto another person’s body. Her head came from a real July 4th parade in Chugiak, Alaska, and the angle and smile fooled a lot of people at first glance—but when you look closely, the lighting, edges, and skin tones don’t match. Even major TV shows have been duped by these fake images, with at least one national host apologizing on air for using them.