As Creative Review reports:

To promote Calvin Harris‘s new single, Sony Music creatives Phil Clandillon and Steve Milbourne (who you may remember were responsible for the AC/DC ASCII Excel video last year) decided to use Bare Conductive, a technology developed by RCA Industrial Design and Engineering masters students Bibi Nelson, Becky Pilditch, Isabel Lizardi and Matt Johnson. Bare Conductive is “skin-safe, conductive ink”. When painted on the skin, it allows a current to be passed through the body without causing an electric shock.

In turn, that conductivity allows human-to-human touch to complete a circuit, generating pre-programmed sounds. All of which sounds a bit daft, as the Brits would say–especially given that the “Humanthesizer” angle here seems designed primarily as an excuse to show pretty ladies in bikinis. But you’ve got to watch the video:

More at CR, including a “making of” video.