I'll tell you why I asked the question - my buddy/guitarist and I were at an open mike evening, we sang 3 songs in the first half and were asked to do 3 more in the second. That was really great, but we'd done everything we'd practiced and I'd just finished with my favorite accapella. The MC insisted we do one more- wow I thought, they really like us. So I called my guitarist back on stage and suggested we do an old song we'd done loads of times before, but not for some time. I got half way thru, then it happened! I turned to him and luckily he remembered the words and just carried on where I'd left off. I laughed and so did the audience and it was great fun. Thanks for all your advice, I feel I have a good collection of tips now. All I have to do is remember them when that blood curdling moment occurs again!