I had never heard of "the bottle-cap challenge"

Trust Ozzy Man to keep you up to date on the latest trends. The so-called "bottle-cap challenge" involves doing a back spin kick* such that your foot barely brushes a loosened bottle cap that's still on the bottle. The cap spins rapidly from the light contact and, thanks to its ferocious angular momentum, pops off the bottle. This apparently must be filmed in slow motion for both dramatic effect and street cred.

Singer John Mayer's kick looks rather sloppy. Stick to singing, J.

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*Joe Rogan, in that kicking video I linked to a while back, notes there's a difference between a spinning kick and a turning kick. The difference is that a spinning kick is more balletic, and the leg's motion starts early as the body rotates around its vertical axis. The kicking foot seems almost to be describing a planetary orbit, sweeping out a Keplerian arc thanks to a straight leg. For a turning kick, by contrast, your body rotates while your leg does very little, and once your body is in position, your tucked-in leg suddenly pistons out, rather than doing a sweeping motion, and your kick will take the form of a fairly standard taekwondo-style side kick. (Rogan demonstrates both kicks in the above-linked vid.) The force of a turning kick comes from the linear thrust of your foot during the piston motion, but also a little bit from the final part of your hips' rotation. Our taekwondo master used to call the reverse turning kick a "back side kick," which isn't a bad way to think of how the kick is executed. I tend to think it's more powerful than a spin kick, not merely because of the directness of the turning kick's motion, but also because of the striking surface—the so-called "knife edge" of the foot, which is good for breaking boards or crushing windpipes.