Just out of curiosity, when your doing a function of some sort and you get the call for Happy birthday, what key do you go for? Unless you have a regular planned key for this as a function band, I usually find that it'll just be either the guitarist or the keyboard player for a simple sing-along. Now, if it's me, I'll usually play a C chord on guitar or a high C bass chord just to give everyone a pitch. However, last week when this happened, the guitarist I was with shouted READY? and hit a G# chord.
Just thought that was a bit weird.