Watch Khloe Kardashian Dare James Corden to Name the Worst 'Carpool Karaoke' Singer

James Corden has shared the carpool lane with some of the biggest names in pop over the past year, from Adele and Mariah Carey to Justin Bieber, Madonna, the Red Hot Chili Peppers, Stevie Wonder, One Direction and Britney Spears. The segments have close to a billion views to date and provided endless joy to so many viewers.

But the real question on everyone's mind is: Who was the worst "Carpool Karaoke" guest of all time? At least that's what Khloe Kardashian wanted to know on Wednesday night's (Jan. 11) episode of the Late Late Show, when she sat down with Corden for the latest edition of his signature gross-out segment "Spill Your Guts or Fill Your Guts."

You know the rules by now: either answer the question or eat something seriously vile -- like, say, a 1,000 year-old egg or a sardine smoothie. Corden went first, daring Kardashian to down a glass of cod sperm or reveal her least favorite E! network show featuring someone in her extended family. Suffice it to say that Khloe was more than happy to throw brother Rob, as well as half-brother Brody Jenner all the way under the bus.

On his first turn, James opted to skip the bird saliva (and potentially lose a booking) by saying that Pierce Brosnan once, literally, pushed him out of the way at a U2 concert. But what happened when the bowl of chicken feet came James' way and she asked "whose been the worst singer on 'Carpool Karaoke'?"

"I just think it's so unfair to answer that," a glum Corden said. "I mean, I could tell you who it is..."

Watch the segment to find out his answer: