Paul McCartney has written a children's book called Hey Grandude!, a name the 76-year-old former member of The Beatles says came from one of his grandchildren.
"I've got eight grandchildren and they're all beautiful and one day one of them said to me 'Hey Grandude!' I said 'What?' and I thought, I kind of like that," McCartney said in a video he posted Thursday on Twitter.
"From then on, I was kind of known as Grandude."
The picture book tells the story of a grandfather with four grandchildren and is illustrated by Toronto-based artist Kathryn Durst.
"He calls them 'Chillers.' They love him and they go on adventures with him and he's kind of magical," McCartney said.
McCartney is currently on his "Freshen Up" world tour featuring songs from his latest album, "Egypt Station."
The book will be published by Penguin Random House UK and is available for pre-order before it goes on sale in Sept. 2019.