U2 rocker Bono once wrote a song for music legend Frank Sinatra and serenaded him with it in a Mexican restaurant.

The pair became pals after Sinatra invited Bono to appear on his 1989 Duets album - and the Irish rocker took it upon himself to write a song especially for Ol' Blue Eyes.

Bono seized the moment to showcase the track, Two Shots of Happy, One Shot of Sad, during a night out with Sinatra at an eatery in Palm Springs, California.

He reveals, "We went out with Frank to a Mexican restaurant and drank margaritas. I wrote a song for him, and sang it to him at the Mexican restaurant. Sadly he never recorded it."

Bono and band mate The Edge did get a chance to perform the song for Sinatra again - at a special TV tribute to the star on his 80th birthday in 1995 - and his disappointment was further appeased when the icon's daughter Nancy recorded a version of the track for her 2004 album Nancy Sinatra.

Image ©Courtesy Sinatra Family Collection

(This news article provided by World Entertainment News Network)