On Monday, the "Keeping Up with the Kardashians" star shared a photo from inside what looked to be a home gym, which featured workout equipment -- including ropes, resistance machines and a weight bench -- and announced he had jumped back on his workout grind.
"Day 1 all good," he tweeted, adding a strong-arm, pregnant woman and Vulcan salute emojis.
The conversation began when Rob tweeted a photo of him with daughter, Dream, 2, who he shares with his ex-girlfriend Blac Chyna, in honor of Father's Day.
In response, Natti wrote, "Happy father's day! You are an excellent father, I know. God bless you. See you soon!"
"Thank uuu see u soon," Rob replied, adding the devil emoji and some hearts.
However, the little exchange didn't go unnoticed by Rob's sister, Khloe, who wanted to know who this lady was.
"Rob what's going on here?!?! Who is this girl?" Khloe snapped and Rob hit back, "Do I know you?"
After Khloe then said she would "pop up on you ass", Rob replied, "Listen just slow yourself down I'm trying to watch the Dodgers game."
This isn't the first time Rob and Natti have shared love on social media. Earlier this month, the sock designer retweeted a topless selfie of the singer with the words, "Oh hi." Just one day later, Natti posted a photo of Rob with baby Dream.