Paul McCartney says he called John Lennon 'four-eyes' when they argued, and his fellow Beatle called him 'pigeon chest'

• Paul McCartney tells stories about John Lennon in the new Hulu docuseries "McCartney 3,2,1."
• He says the famous songwriting duo used to call each other names when they argued.
• "John had a very defensive way, which was beautiful," he says. "But I was much more open."

Paul McCartney is giving fans a deeper look at his relationship with John Lennon and their years together as The Beatles frontmen.

In the new Hulu docuseries "McCartney 3,2,1," which premiered on Friday, the rocker opens up about his former songwriting partner and their obvious differences.

"Thinking back on it, it's crazy," McCartney says in the first of six episodes. "He wore glasses and I didn't. So if we got into an argument, I would call him 'four-eyes.' Four-eyes! And he would go, 'Pigeon chest!' My chest was not as developed as his, or whatever."

"So you know, we did all that. But these things obviously bring you together," he adds.

McCartney and Lennon were the lead vocalists and main lyricists in The Beatles, which also included drummer Ringo Starr and guitarist George Harrison. The duo had a famously fruitful yet complicated dynamic until the band split in 1970. Lennon was murdered in 1980.

In the docuseries, McCartney reflects on their dissimilar backgrounds, including Lennon's tragic family history, and how this affected their adult personalities.

"I always thought everyone had loving families," he tells producer Rick Rubin, who costars in the series. "Of course, later I found that's not true. And some people are very unfortunate. John was very unlucky. His dad left his home when he was 3, and John didn't see him 'til he was famous. And also John's mom got killed. So this was an eye-opener to me."

As Rubin points out, this "speaks to the difference in temperaments as grown-ups."

"That's true," McCartney agrees. "John had a very defensive way, which was beautiful. It's how he got through that childhood. But I was much more open and just more, 'Everything's great.' Optimistic."

"As a team, that worked," he continues, singing a few lines from their 1967 song "Getting Better." "I would write, 'It's getting better all the time,' and he would go, 'It couldn't get much worse.' Which was like, the perfect foil for that song. So I loved the way he would always add a little cynicism."

Later, in the fifth episode, Rubin reads a quote from Lennon about McCartney's skill and influence as a musician. The "Imagine" singer had called his former bandmate "one of the most innovative bass players that ever played bass."

"That's beautiful. I hadn't heard that before," McCartney replies. "He never said that to me. But it's nice to hear that he said it to someone."