Why did Allu Arjun call Pawan as 'Babai'?

The other day, Stylish Star Allu Arjun gave a detailed explanation on why all the Mega Heroes were not able to grace the audio launch of Pawan Kalyan's 'Panjaa'. And what surprised everyone was, Bunny addressed Pawan Kalyan as 'Babai' instead of 'Mavayya'.
"Just because we didn't attend the audio launch doesn't mean that there is a split between us. We don't mind if media criticizes our films, but scrutinizing family relations is not fair. I'm hurt by the reports in media. We are all united and will be," said Allu Arjun.

"I wish Kalyan 'Babai' all the best. I hope Panjaa will be great film. Our fans are waiting to see Kalyan 'Babai' in another Blockbuster," he added.
According to the sources, the reason for Bunny calling Pawan as Babai is a result of strong bonding between the family members of Chiranjeevi.
"Since their childhood both Bunny and Sirish has a habit of calling Chiranjeevi and Pawan Kalyan as Babai along with Ram Charan. All the kids in the family grow up together, so we often see some resemblance between them," said Bunny's PR.
It's good to see such a great bonding in a celebrity family. Chiru who is the head of the family should be given credit for making this happen. That's the story of Mega Family and Mega Bonding!!!