Stevie Wonder made a surprise and unpublicized appearance on 'American Idol' tonight, singing his 1970 classic 'Signed, Sealed, Delivered (I'm Yours)' in front of the 'American Idol' hopefuls.

The music legend's appearance was perfectly timed and beyond appropriate, since many of the contestants chose to perform Wonder's hits last night for 'Motown Week.' The class of Season 10 did not join Wonder for his performance, but we sure hope they were taking notes, because they were in the presence of exactly the type of greatness they're all aiming to achieve.

But Wonder didn't just perform one song and then sign off! Before leaving, he called out Steven Tyler and  launched into a rendition of 'Happy Birthday' for the judge, who will celebrate his 63rd birthday on Monday. What better present can he possibly expect to get than a serenade from the one and only Stevie Wonder? Tyler's a lucky man.

Another surprise guest this week was professional wrestler Hulk Hogan, who took the stage to let contestants James Durbin and Paul McDonald know that they were safe from elimination this week. Of course, "the Hulkster" also tore off his shirt, which was his signature move long before Chris Brown was even born.

Watch Stevie Wonder perform 'Signed, Sealed, Delivered (I'm Yours)' on 'American Idol'