Bad boy Chris Brown just can't keep his hands off the Jenner girls!

After reportedly breaking up with on-again-off-again girlfriend Karrueche Tran this week, the singer posted a photo with Kendall Jenner sitting on his lap, sis Kylie practically wrapped around his waist, and step-sister Khloe Kardashian with her hand on Kylie's butt! Bet Karrueche loves that!

To make matters worse, Complex Magazine quoted Brown in a Tweet: "I'm single too, f**k that b****," Chris Brown. #CaliChristmas."

Dang! It's a war of words -- Karrueche followed with "N****** be in they feelings when you break up with them lol." She later expained, when commenters asked, "I was talking about the show Single Ladies ... I just came back from shooting an episode lol gee wiz."

Uh, yeah ... well, it's ON now! And as usual, the Jenner girls are in the thick of the action. Are they the go-to girls when guys ditch their ladies? Not so hot to be the rebound girlz all the time, K & K.