I got my 'tash caught in the slide of a chromatic gob-iron once. Brought tears to my eyes...

Other not quite malfunctions but things that fit the bill are Frank at our club borrowing Mikes 12 string guitar for a gig only to find when he put it on to play that Mike had failed to mention that he was left handed. Spot the Dog of this very cafe once opened his guitar case at a methodist chusrch hall only to be reminded that he had filled it with cans of Guinness. Just as they spilt all over the stage!

Oh - and I distincly remember a singers malfunction when he sang My father was a fisherman. My mother was a victory V...

Cheers

DtG