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Rihanna and Eminem are among the latest stars taking on the ALS Ice Bucket Challenge.  The two chose the final date of their joint "Monster" tour Saturday in Detroit to douse each other in ice live onstage. 

The rapper was challenged to the viral charity fundraiser by Dr. Dre.  RiRi did the honors by pouring the bucket over his head as his hometown sold-out audience of 45,000 went wild.  He returned the favor, challenging her right away.  She joked with the crowd before finally sitting down to get soaked. 

The video posted to Eminem's Facebook page was the closing act of their six-date tour, which earlier stopped in New Jersey and Los Angeles. 

Check it out!