Late country legend Johnny Cash used to phone close friend Willie Nelson in the middle of the night and demand to hear funny jokes.
Cash, who died in 2003 aged 71, met Nelson in the 1980s when they both joined musicians Waylon Jennings and Kris Kristofferson to form the country supergroup The Highwaymen.
The pair became close friends while touring the U.S. - and in his later years, Cash often turned to his former bandmate when he needed a laugh.
Nelson recalls, "He had a great sense of humour. I'm about a half-assed joke teller! I love to tell jokes and he would call me numerous times, even in the middle of the night.
"He was somewhere, I was somewhere and he'd want to hear a good joke because he needed a laugh.
"I'm sure in the final years of John's life he did need a laugh a lot of times."