It's a guy, throwing a ball against a mirror and filming it on his phone.
What appears, at first to be a perfectly innocuous clip, suddenly becomes really freaky. How exactly is that happening?
Filmed by Kevin Parry, at his home in Oregon, the short video has gone viral and unleashed a furious debate about what is going on. Are there two Kevins? Is it actually a mirror or not? Is it magic?
And if you want to know, take another look at it below and we'll tell you...
Slow the clip down to 0.25 (using Settings -> Speed), then watch carefully between 6 and 7 seconds. At the apex of the arc, the ball mysteriously jumps up - so this is (at least) two different clips edited together. Nice try though Kevin...