Then of course there was the gypsy fiddler, who suddenly re-appeared in front of schocked diners with his instrument but wearing no clothes. One of the diners turned to him and said:-

"Actually I said "Can you play "In the Mood"?"

Not a gig blooper this but an ex-flatmate of mine said he was a shepherd in a school Christmas production and the teacher had written this line for him to say:-

"Oh that I, such a humble shepherd , should live to see such a sight as this"

You can guess the rest!