Just when we thought we saw every single one of Kylie Jenner's growing-up milestones on Keeping Up With The Kardashians, we find out about this one that she somehow snuck past us!

During a video segment for Kylie's Clique on her app, the 18-year-old was chatting with her pals Stas and Sham and when the subject of Kylie's first kiss came up, she didn't shy away from it.

The reality star casually revealed that her first kiss was in fourth grade - if you're counting just a peck. If you're counting a kiss, kiss, that didn't come until seventh grade.

Of course, we were all dying to know WHO the lucky guy who got to lock lips with Kylie was and not only did she reveal his name, she CALLED him during the segment.

"My first kiss was to Matthew in Zoey's backyard," Kylie explained. "I still have his number, I can call him." And that's exactly what she did.

When she got a hold of him, Matthew didn't quite remember things the way Kylie did -buddy, how could you FORGET kissing Kylie Jenner?! - but after Ky gave him a quick refresher course to jog his memory, the kiss was confirmed! #SealedWithaKiss