Lots of things in football cannot be explained - why is Alan Curbishley still unemployed, how is Hilario still a Chelsea player, and what does Vincent Tan think he looks like when he dons those black leather gloves?
Anyway, add this to your list - a thoroughly baffling video from our South American friends in Bolivia.
At a local match in the country's third largest city, La Paz, the cameraman got bored with the action as his gaze slowly wandered up towards the crowd.
And to his surprise, he caught on film a pretty bizarre sight - a shadowy figure gliding across the stadium with some pace.
We're not sure what's going on here - some have suggested it's just someone running along the bleachers.
But look closely. He glides right through the other people who are standing to watch the game, and doesn't break stride as he moves across the tarpaulin that separates the fans on the right of the picture.
And is he really running? Look again, he seems to be taking really quick, but large, strides across the ground. He's not running like anyone I've ever seen before.
Also he's moving way too quickly to be running the speed any normal football-supporting human could expect to reach. Spooky.
Think you can explain the clip. Have your say below...