The 56-year-old actor - whose wife Kelly Preston gave birth to Benjamin in November - is a hands-on dad and loves to find new ways to entertain the tot when changing his nappy.
He explained: "I make up songs. I was changing him the other day, and I wanted to entertain him so he didn`t get upset, so I made something up."
Kelly, 48, admitted while she can`t see any resemblance between herself and Benjamin, she thinks he looks "identical" to his father.
She said: "Maybe there`s me somewhere in there, but he looks so much like his daddy."
Although the proud parents attended the G`Day LA Black Tie Gala at the Hollywood on Saturday (22.01.11), they were forced to leave early so Kelly could nurse her son.
John said: "It will only be an hour and a half that we will be away from home because she is clearly breastfeeding.
"We have geared the team at home. We all have cell phones. It will be good."
Kelly added: "I called home three times in the last hour and he`s doing well. He`s perfect! He`s fine."
Kelly and John`s eldest child, 16-year-old Jett, tragically passed away two years ago when he suffered a seizure while on a family holiday in the Bahamas and the actress - who also has a daughter Ella Bleu, 10, with her spouse - says Benjamin has brought the couple closer together.
She said: "All of our children make us just so much closer. Benjamin is just dreamy."
John added "Ella loves Benjamin. She just can`t stop loving him."