The 29-year-old reality star shared his 19-year-old half-sister's phone number online Monday amid drama over Blac Chyna and an upcoming baby shower.
"Kylie's # +# (###) ###-#### I ain't hacked either this rob dog lol," Kardashian tweeted to his 6.7 million followers, adding several tears of laughter emojis.
"Didn't invite the Mother of my child to a baby shower you all were trying to throw for me!? You all must have lost your damn minds," he seemed to explain minutes later.
Blac Chyna had announced on Snapchat earlier in the day that her baby shower will take place Sunday. Sources told E! News that Kardashian's family planned a separate party specifically for the dad-to-be.
"Rob couldn't attend, so Chyna was going to attend and Kim [Kardashian] said if Rob didn't go, then Chyna couldn't go. It sounds like that's what caused the argument," an insider said.
Blac Chyna and Jenner previously had tension over Jenner dating Blac Chyna's ex-fiancé, Tyga. The 28-year-old model admitted in the October issue of Elle, however, that she wasn't upset when her relationship with Tyga ended.
"I was just like, 'Thank God I'm out of that situation.' And honestly, it was the best thing that I could've done, because my life has changed so much for the better," she said.
Kardashian and Blac Chyna got engaged in April after three months of dating and announced they're expecting the next month. The couple star on the new E! series Rob & Chyna, which airs Sundays at 9 p.m. ET.