EXCLUSIVE: James Corden 'Stole' Jennifer Lopez's Phone and Texted 'the Most Famous Person on the Planet'

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Jennifer Lopez graciously accepted James Corden's request to star in his first primetime karaoke special, but you won't believe how The Late Late Show host returned the favor.

"I stole her cell phone," Corden told ET. "You've never seen more famous people in your life!"

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After perusing J.Lo's star-studded rolodex, Corden said that he texted "the most famous person on the planet" from the singer's phone -- and actually got a text back!

Despite Corden's status as a late night talk show host, the 37-year-old British comedian still gets star struck, and he rattled off a few of the big carpool karaoke guests that he was the most excited about driving around.

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"You never think you're going to meet Stevie Wonder," Corden said. "Singing Elton John's hits ... I thought, 'If these were auction prizes, they would go for hundreds of thousands of dollars, and yet this is my job.'"

The Late Late Show Carpool Karaoke Primetime Special airs Tuesday at 10 p.m. ET/PT on CBS.