Putting each other to the test! In a new video posted on Kourtney Kardashian’s website and app, the reality star challenged sister Khloé Kardashian to a fun game of ‘Know Thy Sister’ to find out which of them knows the other one better.

“You guys know I love a little friendly competition, and some of these questions were hilarious,” Kourtney, 36, captioned the video, which is labeled ‘Part I.’ “Watch the whole video to see who won this round, and be sure to check back soon for the next one!”

First up, the Keeping Up With the Kardashians stars were asked what Khloé’s favorite color is.

“I think everyone in the entire universe knows that answer,” Kourtney joked, as she wrote down “purple.”

When Kourtney was asked what age Khloé was when she lost her virginity, she simply responded, “I think it was 15.” Khloé stayed quiet, but confirmed the answer when she turned around her whiteboard, which she wrote “15” on.

Next, the pair went head to head as they tried to remember what Khloé’s favorite band was in high school. She ultimately revealed that she was a big fan of ’NSync, Backstreet Boys and Ace of Base.

The Kocktails With Khloé host, 31, then had to guess her older sister’s favorite Disney movie.

“This isn’t fair because I like them all,” Kourtney explained, before selecting Peter Pan. Khloe yelled, “That is so your movie!”

Watch the full video on Kourtney's website to find out what else the sisters revealed — including when Kourtney had her first kiss and which exercise Khloé hates the most.

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