Bicostal booty call!

Kendall Jenner and baller beau Ben Simmons are "not exclusive" but still "hooking up" according to a recent report and it seems like Kenny totally into that idea because we spotted her hopping on an early-morning flight headed to Philly today!

The supermodel and the NBAer, 22, have been "hooking up" for months now, off and on, but it seems like it's a comfortable situation for Jenner, 23, because she's racking up mileage for the D! "He’s in the spotlight and understands that they need to be on the down-low. He also travels and works as much as she does, so it works for them," a source tells the mag. "Kendall values her privacy more than any of her sisters, so you will rarely see [her and Ben] out together officially."

The two supposedly split in September but apparently they never really gave up on the hookups!