Rufus Wainwright, Sean Lennon Perform Madonna's 'Material Girl' At Occupy Wall Street Protests (VIDEO)

It's a rare moment when one of the world's biggest gay icons pays tribute to another -- and rarer still when it's done for a worthy cause.

But that's exactly what happened this week when Rufus Wainwright lent his voice to an impromptu, tongue-in-cheek version of Madonna's "Material Girl," during his surprise appearance with Sean Lennon at the Occupy Wall Street protests. With its seemingly pro-capitalist stance, the 1985 classic may seem like an unlikely protest anthem, but the Canadian singer-songwriter nonetheless sang along to the tune with the gleeful crowd at Zuccotti Park while Lennon accompanied on guitar.

Writes one user: "Are they occupying wall street or repealing 'don't ask don't tell'?"

It's not the first time the 38-year-old Wainwright has paid homage to a diva. In 2006, he performed a critically acclaimed, song-by-song redux of Judy Garland's legendary Carnegie Hall concert.

Watch Wainwright and Lennon's OWS performance below: