KINGS OF LEON PAY TRIBUTE TO RYAN DUNN

The band Kings of Leon honored their friend Ryan Dunn at a concert in London this week ... asking the crowd to make a toast to "a friend of ours who passed away" ... before playing a song in his memory.

The band then broke into a rendition of their song, "McFearless" ... and lead singer Caleb Followill told the crowd, "This is for Ryan."