For Van Halen fans, the middle aughts were certainly interesting times.

Largely silent since the late '90s, the band muddled through a disastrous, short-lived reunion with former singer Sammy Hagar in 2004, and guitarist Eddie Van Halen — who'd been battling cancer that he later claimed he'd cured through "not exactly legal" means — seemed shrouded in erratic behavior.

Arguably the oddest of Eddie's decisions — at least on the musical front — took shape in the form of his contributions to the soundtrack of Sacred Sin, an adult film by director Michael Ninn. Van Halen contributed a pair of tracks to the movie: "Catherine," which you can listen to above, and "Rise," which you can hear below. For fans who'd been waiting patiently for new music from one of rock's reigning guitar gods, the news wasn't exactly unwelcome, but it was perplexing — as was Van Halen's justification for ending his hiatus in the name of softcore art.

"I’m working with a friend — very simple," he shrugged. "I like his work. Michael Ninn is like a Spielberg to me: the imagery, the way he makes things look just ... sensual."

Starring Penthouse pet Heather Vuur, the film uses a supernatural story to weigh in on themes that add up to what the synopsis describes as "the story of how we handle the pain of loss, the story of how our innermost sexual mechanisms help us cope, or give up faith completely." Of course, heady metaphysical themes weren't exactly the major selling point for many Sacred Sin consumers — or a big part of the release party Van Halen threw on Sept. 30, 2006.

Photos and footage from the event (obviously NSFW) later surfaced online, and by all accounts, it was a night to (hazily) remember. "Let me describe the evening for you," recalled one alleged attendee. "Naked porn chicks in Eddie's pool followed by naked porn chicks licking each other in and out of the pool. Acrobats hanging from the ceiling (kind of a Cirque de Soleil show) and drinks everywhere."

"There were scantily clad and/or naked chicks everywhere, there were half-naked Cirque du Soleil-type performers doing acrobatics in and outside the house, there were guys on stilts walking around, there were rock stars and porn stars galore," added another partygoer. "There was an open bar, tons of great food and hor's d'oeuvres, plus Eddie played a set of Van Halen songs with an all-star backing band, and later entertained a small room with a piano recital."

Fortunately for Van Halen fans, Eddie wasn't about to give up his day job. The following year, the band reunited with original singer David Lee Roth, mounting a North American tour that rolled over into the summer of 2008 — and ultimately produced the band's first album in more than a decade, A Different Kind of Truth.

Van Halen Albums Ranked Worst to Best