Big guitars and piano accordians could save a lot of embarrasment. Pity the poor tin whistle player!Serious suggestion - We tried a singers session where the singer nominated the next singer and, possibly, song. Worked very well but you realy find out who your friends are! Or how about a fancy dress night where everyone turns up as a character from one of their songs?
Let us know what you come up with and, better still, what works best - I am always one to learn from others mistakes;-)
Cheers
DtG