The Arthur George sock designer, 29, laughed while recalling the past with his pregnant fiancée, Blac Chyna. "Her childhood crush is Ricky Martin," he said of the model, 28.
"Livin' la vida loca!" Chyna chimed in, belting out the singer's 1999 hit. She then put her husband-to-be in the hot seat.
"J.Lo," she said of his previous crushes. In addition to Jennifer Lopez, she named Kim.
Rob awkwardly grinned and replied: "That is also pretty accurate."
Chyna added: "These are facts."
Viewers were left baffled by his revelation. "So Rob used to have a crush on Kim? I can't keep up with the kardashians anymore!" one commenter tweeted on Thursday.
A second posted: "Uh… I'm feelin' weird about Rob Kardashian saying he had a childhood crush on Kim…"
Chyna, meanwhile, found the situation amusing. She and Kim, 35, have been friends for years, and the Selfish author has been supportive of Rob and Chyna's relationship since its early stages. The future spouses recently hit a rough patch though.
"They are not in a good place right now. Filming the show has been a lot of stress on their relationship. Add to that Chyna's pregnancy and the fact that Rob and his moods go so up and down," an insider told Us Weekly on Wednesday. "[But the family is] confident that they will get through it and patch things up."
Hours later, Rob posted a cute video of Chyna's bare baby bump via Snapchat as they relaxed in bed together.