Credit: Jason Merritt/Getty Images Photo: Jennifer Aniston at Call Me Crazy Premiere

You've seen the marks on Jennifer Aniston, Chris Martin, and other celebs: the cupping marks! Mysterious, perfect circles have been popping up on celebrities' backs all over the place — even Olympian backs. But how did they get there? David Arquette has posted a photo before, but the angle wasn't the best for seeing what it's about.

Luckily, Olympic Gold Medalist swimmer Natalie Coughlin posted some much clearer, much more graphic, photos of the process for the curious! In a two-shot series on Instagram, the athlete said, "Torture Natalie Wednesday! #HurtsSoGood." Yikes!

Cupping is a form of alternative medicine slightly related to acupuncture that involves setting cups on skin to make a suction sometimes by pumping the cup, and sometimes by burning the cup before applying it. WebMD says that supporters believe this mobilizes blood flow.

See the photo below!

Yikes! Have you gone cupping? Would you?