Hold up before you click, because those “look now” posts are everywhere, and the headline always sounds wild. Today it’s claims of Sarah Palin in a tiny bikini that supposedly leaves nothing to the imagination. Stay with me until the very end, because I’m going to give you a fast, simple test you can use to spot a fake photo in about five seconds.

I’ll also show you the one background clue that gives many of these viral images away instantly. Watch closely, because once you learn this, you’ll never fall for clickbait the same way again. Here’s the truth you need first. For years, edited images of public figures have been pushed online to trigger shock before facts can catch up. One of the most famous examples 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 it was a composite. Her face was taken from a real photo and pasted onto someone else’s body. The original image of her head came from a July Fourth parade in Chugiak, Alaska. The angle, smile, and lighting were close enough that it fooled a lot of people at first glance. But when you slow down, the edges, skin tones, and lighting don’t match. Once you see it, you really can’t unsee it. What makes this even more important is that it didn’t just fool random accounts online.