'American Idol' Hopeful Jason Castro's Secret Weapon: Bruddah Iz

Late Hawaiian singer's arrangement likely to save the dreadlocked one from elimination.

There's no question Jason Castro's Tiny Tim-esque rendition of "Somewhere Over the Rainbow" was one of the more memorable performances on "American Idol" Tuesday night — one that will likely spare him relegation to the show's bottom three. Castro shined as he gently strummed his ukulele and swooned, much to the delight of the dozens of fresh-faced preteen girls who were huddled together at the edge of the "Idol" stage, not to mention John Norris.

Like Castro's earlier performance of Jeff Buckley's impassioned cover of Leonard Cohen's "Hallelujah," which was hailed by the "Idol" judges for its originality, the dreadhead's take on "Somewhere Over the Rainbow" was praised once again for its brilliant execution. But both Castro and judge Simon Cowell made sure credit for the arrangement was given to a Hawaiian treasure named Israel Kamakawiwo'ole, who was affectionately known as "Bruddah Iz" by the island dwellers.

(Castro isn't the only contestant known for covering covers. Check out the reactions to David Cook's second-hand renditions.)

Unfortunately, Kamakawiwo'ole will never know just how much his version of the song helped Castro's cause, as Bruddah Iz — who, at last count, weighed 758 pounds — passed away more than a decade ago, due to a weight-related respiratory illness. He was only 38 years old.

Not long after his death, Iz's coffin was laid out for mourners in Hawaii's Capitol building, so that fans could pay their final respects. He's only the third person in Hawaiian history to be accorded such an honor, and the only non-politician. An estimated 10,000 attended Kamakawiwo'ole's funeral and cheered as his ashes were scattered into the Pacific Ocean.

Chances are you've heard Iz's take on the "Wizard of Oz" classic, because it's graced the soundtracks of "Meet Joe Black" and Adam Sandler's "50 First Dates." The song has also appeared in commercials and punctuated the death of Dr. Mark Green on the TV drama "ER." Iz's version of the song experienced a huge jump in sales following Tuesday's episode and is currently #14 on iTunes' top-downloads list.

According to Billboard, Iz still sells tons of records, posthumously. Back in 2004, the song reached #12 on Billboard's Hot Digital Tracks chart, and the track continues to be a low-charting but steady seller, passing 1,040,092 downloads as of last month. Last July, Kamakawiwo'ole's Wonderful World opened at #44 on the Billboard albums sales chart, selling more than 17,000 units. It was Iz's biggest sales week ever.

For Castro, "Somewhere Over the Rainbow" could end up being the song he's most remembered for, when all is said and done — much like it was for season-five runner-up Katharine McPhee, whose performance judge Randy Jackson applauded as "amazing and hot." It even melted the heart of the surly Simon Cowell, who called it her best performance of the season.

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