On Sunday's "KUWTK," Khloe snaps at Kourtney while the sisters are in San Francisco -- and Kourtney fires back.
In the clip below, the three Kardashian sisters are on a nighttime boat ride in San Francisco, passing by the historic Alcatraz Island. While Kim and Khloe are snapping photos of the landmark, Kourtney is off in the distance, finishing up a phone call.
"What the f-ck are you here for?!" Khloe fires at Kourtney after the latter tried to comment on the view. "Don't chime in if you're not gonna -- get off your f-cking phone call! You're like a waste of space in my meter right now."
"I'm looking at everything," Kourtney says after hanging up.
"You're annoying as f-ck now that we're together," Khloe says. "This is what you do. You're on your phone the whole time. You're just not present."
"I had a 10-minute conversation with Sarah, and that's offensive?" Kourtney asks.
"Yes, because we're only here once! When are we ever gonna go back to Alcatraz?" Khloe says.
The argument grows more and more intense until Kourtney shouts, "F-ck you, you f-cking whore! You f-cking pregnant whore!"
Kim's only contribution was, "Throw her over! Let's throw her over," in reference to Kourtney.
The season finale of "Keeping Up With the Kardashians" airs Sunday at 9 p.m. ET/PT on E!