Tyga may be pretending to be happy about his baby mama Blac Chyna's engagement to Rob Kardashian, but behind the scenes, he's fuming.
The rapper is reportedly incensed over the bond his son King Cairo has formed with Rob, who has become quite fond of the three-year-old, according to Radar Online.
"Rob spending so much time with King Cairo is really starting to get to his father Tyga," a source told the site.
In fact, King has even started referring to Rob as his father.
"King has already started calling Rob 'Daddy,' and this drives Tyga absolutely nuts!" added the source.
"Tyga told Blac Chyna several times that he does not want King calling Rob 'Dad' ever!"
Tyga is currently on tour in Australia, and he's blowing his top down under.
Meanwhile, Rob and Blac took King on a field trip to the firehouse earlier this week, where the tyke got to sit in an actual fire truck and talk to the firefighters.
Blac made sure to share the experience to Instagram, which likely sent Tyga stewing.
Rob is reportedly having so much fun with King that he wants to have a baby with Blac right away, and reports say they've already picked out a name.
Their progeny shall be called Robert III.