If you've seen this, you haven't drunk too much out of the wrong bottle. It's just an anamorphic optical illusion. Photographer Joseph Ford arranged this composition with the assistance of artists and parkour athletes.
Together, they created the impression of a tennis game over and in an abandoned swimming pool in Glasgow, Scotland. They mapped and laid out 2.5 kilometers of blue tape in the pool, along the walls, and in midair to create this impression. It's even more bizarre once the parkour athletes start their gravity-defying moves. You can see more photos at Design Boom.