Keith Moon was apparently a wild party guy - well known for lots of drugs and alcohol and trashing hotel rooms. Maybe not the safest guy though. I saw an interview with Joe Walsh awhile back, and he said one of the worst things that happened to him in his early days was that Keith Moon took a liking to him, and he started partying with Moon and fell into the same pattern of destructive behavior. Walsh said it with a laugh, but it seemed pretty clear he recognizes how dangerous his lifestyle was at that time.
This is interesting because my first thought was that this tune was too recent for Bob Marley too have sung before he died, so I wondered if it was actually a Bob Marley tune and Bobby McFerrin's version was the cover. I looked things up and found McFerrin wrote the song, and recorded it in 1988. Bob Marley died in 1981, so apparently McFerrin wrote it years before he recorded it, and Marley recorded McFerrin's song before McFerrin did himself