In a sneak peek from Sunday's episode of Keeping Up With the Kardashians, Kim, 30, puts her NBA player beau, 26, on speakerphone to chat with Kourtney prior to their Bora Bora vacation.
"Kourtney, just because you have a kid and you don't do anything fun does not make you mature," Humphries tells Kourtney, 32, out of the blue.
Will Humphries win Kourtney's seal of approval? Watch Keeping Up With the Kardashians when it airs Sunday at 10 p.m. EST on the E! Network.