In things we never thought we'd report, Jaden Smith -- son of Will and Jada, star of 'The Karate Kid' reboot -- is dating Kylie Jenner.

Us Weekly reports that Smith and Jenner hung out a bunch in London recently and were photographed being cute teenagers together.

"They're dating," a source. "It's new, but they've been friends forever."

To give some perspective on "forever," Smith is 14. Jenner is 15.

The pair had a lunch date in the U.K. capital, where Smith had been on hand to celebrate BFF Justin Bieber's birthday -- and end up cutting his pal's party short because he was underage. (Biebs denied this later on, but Us insists it's true.)

If you'll excuse us, we're going to go back to feeling old and wondering where their parents are.