Beyonce might be the person who's taking the most heat for lip-synching at this precise moment in time, but she's far from the first performer who has relied on a backing track of some sort. While she stands a good chance at recovering from her national anthem trickery, some earlier musical offenders weren't so lucky.

Milli Vanilli was famously stripped of the best new artist Grammy in 1990 after it was discovered that they -- Robert Pilatus and Fabrice Morvan -- didn't actually provide the vocals used on their "Girl You Know It's True" album. Below is one of their hit songs from the album, "Girl I'm Gonna Miss You," which hit the top of the charts when it was released in 1989.

There's the behind-the-scenes lip-synch, and then there's the live, right-before-your eyes reveal. Despite the fact that the original clip has pretty much been scrubbed from the Internet, Ashlee Simpson will long be remembered for her "Pieces of Me" fail on "Saturday Night Live" in 2004. The music started, but her mouth didn't really move, and Simpson did a little jig to deflect the awfulness of the situation. (Catch some of it around the 3:50 mark of this video.)

In October 2012, Justin Bieber made headlines for throwing up on stage -- hey, stars get the flu, too! -- but the other takeaway was that while the singer was losing his lunch, he managed to keep on "singing."

Pop stars aren't the only ones guilty of relying on pre-recorded vocals. Is rapper Eminem's mouth keeping up with the vocal track here?

At the 2007 BET awards, 50 Cent skipped the entire first verse for "Amusement Park" and wandered the audience until catching up with the song. Did he forget the words? Later he said, "I just wasn't concentrating."

These examples just scratch the surface; where proof exists of one artist lip-synching, there are scores of allegations that others are doing it, too. Mariah Carey, Britney Spears, Madonna, the list goes on.

Are you bothered by lip-synching or is it enough to see a performer live on stage, whether he or she is actually singing or not? Weigh in on Facebook.

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Eminem turns 40 Wednesday, and it's tough to think of the often-controversial rapper as middle-aged. After all, he once sang about slitting his wife's throat. It's not likely he'll sail into a comfortable old age wearing cardigan sweaters and puffing on a pipe, all Bing Crosby style. (Although Der Bingle had his own family issues.)

Slideshow: Eminem

Andrew Medichyini / AP

Launch slideshow

Eminem's hometown paper, The Detroit News, noted that he's in good company in the 40ish rapper club, as Jay-Z is 42 and Dr. Dre 47.

The paper also celebrated the rapper's big 4-0 by choosing Eminem's top 40 songs.

No surprise, Oscar-winning "Lose Yourself," from his 2002 film "8 Mile," sits at No. 1. And yes, grisly "Kim" is No. 2, with equally bloody obsessed fan tale "Stan" at No. 3. "97 Bonnie and Clyde" is their pick for No. 4, and the catchy, pop-culture-reference-filled "Real Slim Shady" is at No. 5.

At 40, he's still the Real Slim Shady.

"American Idol's" first champ, Kelly Clarkson, proved during a Friday night concert that she can do more than just belt out huge tunes. Girl can also cover a rap song like you wouldn't believe.

While performing in Eminem's hometown of Detroit, the Grammy-winning songstress treated the crowd to "Lose Yourself," the hit from the rapper's 2002 film "8 Mile." Clarkson explained to the audience that several fans had asked that she perform the rap tune for the segment of her concert that she devotes to requests. 

"I went from Texas to thug, ya'll!" she joked before launching into the song. Check it out:

Not bad, right? Compare it to the original:

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We've always liked the Real Slim Shady. Apparently 60 million other people do, too! Eminem is the most popular artist on Facebook and was recently the first to accumulate 60 million fans on the social networking site.

Jason Decrow / AP file

Thumbs up? Facebook users really, really like Eminem.

He even beat out Lady Gaga (53 million fans) and Rihanna (59 million fans) in this cyber-popularity contest.

Find out which celebs cashed in on Facebook's IPO

But while the "8 Mile" star is the reigning king of Facebook, Gaga and Rihanna are Twitter royalty. Gaga rules the microblogging site with 27.8 million followers, narrowly beating out Justin Bieber and his 25.8 million Beliebers. With 23.4 million followers, Rihanna's doing pretty well on there, too. Eminem, however, lags behind his fellow artists with only 11.8 million followers.

Time to step up that Twitter game, Em!

Check out some of our fav Twitpics!

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