The latest spot for Old Spice starts off in typically insane fashion. Perpetually amped spokesman Terry Crews is seated, stripped down to tiny red shorts, with EKG sensor pads all over his body. He’s completely surrounded by musical instruments and other odd equipment that looks like it up and walked off the set of Peewee’s Playhouse . In other words, we are in familiar territory. It’s only once the ad ends that the proceedings truly venture off the beaten path.

In “Muscle Music,” those sensors on Crews’ body are rigged to corresponding musical instruments. Each time the massive spokesman flexes his muscles, a note of some kind sounds–most memorably, perhaps, a “flame sax” at one point. After the ad is over, though, comes the ultimate Easter Egg: Users can actually “play” the strange orchestra themselves.

When the time runs out at the bottom of the Vimeo player, a record button appears. Users are then encouraged not-so-politely by a suspended animation version of Terry Crews to explore the musical space by tapping keys: “”Hey, play the music or get out.” Advertising agency Wieden+Kennedy Portland teamed on the project with Tom Kuntz, the director behind “The Man Your Man Could Smell Like” and other Old Spice hits, as well as Vimeo, VFX company The Mill, and editing house Mackenzie Cutler.

“Working directly with Vimeo, we created a never-been-done-before digital experience directly within the Vimeo interface,” says Mike Davidson, Senior Interactive Producer at W+K Portland. “Our custom experience lives within the Vimeo player, allowing viewers to ‘play’ Terry Crews anywhere the experience is embedded–Facebook, Twitter, Blogs, etc.–without ever having to leave that site. The ‘Terry Player’ functionality is then attached to the end of each user-created video, making this a truly unique, customizable shared experience.”

Jason Bagley and Craig Allen, the W+K creative leads on the project add: “We’ve learned over time and deep study that Terry Crews’ muscles are big, strong, and very capable of flexing. One of our teams, Max Stinson and Andy Laugenour, figured: why not selfishly harness that powerful flexing to create music. It started off as a funny music video that turned into an interactive video that turned into joy for our eyes and fingertips. We couldn’t have done this without our powerful allies Tom Kuntz, The Mill, and, of course, Vimeo. “