Eminem's birthday is coming up on October 17, but we need to celebrate Shady for more than one day of the year. And that's because he's one of the most creative and hilarious artists of all time. We've got the throwback footage to prove it, too.

Back in 2000 Em made fun of everyone and their mom in "The Real Slim Shady" video, and that included Britney Spears, who was the reigning pop queen at the time. He really got into character -- rocking her outfit from the "Baby One More Time" video and the behind-the-scenes footage of him transforming into Brit is priceless.

Marshall didn't seem to fully realize what he was getting into here, but by the time he was wearing false eyelashes, lip liner and a blonde wig, he was ready to roll with it.

Check out the silly footage above.