Donate to charity for a chance to party with Robert Downey Jr.

Last week, Robert Downey Jr. simultaneously revealed the Iron Man-themed poster for Avengers: Age of Ultron and promised a "big announcement" arriving eight days later.

While the aforementioned announcement isn't slated to arrive until Thursday, Downey took to social media again today to promote his and Marvel Studios' involvement in a promotion for Julia's House, a children's hospice charity.

In a video posted on YouTube, the actor promises one lucky winner the "best night of your life. On Earth. Yet," with a helicopter ride, indoor skydiving, sharing caviar with RDJ and a walking together down the red carpet for the world premiere of Age of Ultron. There's a minimum entry donation of $10, and varying levels of donations receive different pieces of Avengers merchandise.

Those interested in entering can do so at http://omaze.com/rdj .

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