The star of HBO's television series Vinyl has explained that unlike his and girlfriend Rose Byrne's baby Rocco, whom he can kiss as much as he likes, his older son Jake Cannavale is at an age where he tends to reject displays of affection.

"He's got tattoos, he's got hair everywhere, he's literally the only guy on the planet that I'm dying to kiss me, and he won't kiss me," Bobby said during an appearance on The Tonight Show with Jimmy Fallon on Monday night (04Apr16).

Bobby also joked that Jake, his offspring from his marriage to screenwriter Jenny Lumet, doesn't have the same aroma as his new tot.

"I have a son who's going to be 21 next month, and he does not smell good," he laughed, adding, "He's cute but he doesn't smell good, so it's a weird juxtaposition to have."

Looking sharp in a grey three-piece suit with a black shirt, Bobby continued to gush that himself and Bridesmaids star Rose, 36, are thoroughly enjoying parenting their baby son Rocco together since he was born in February (16).

"It's pretty blissful, it's nice. Babies just make you happy right," he shared. "He's sweet; he's a really good boy. He smells really good."

Bobby can't help but share adorable photos of baby Rocco with his friends, but he feels most people aren't all that interested in looking at baby snaps.

"They don't care, it's only after you've shown them 10 pictures you realise they didn't care after the first one," he grinned.

Bobby and Rose began dating in 2012 and have since worked together 2014's drama Adult Beginners as well as 2015's action comedy Spy.