There are some songs I sing, particularly Postman's Knock from Adderbury (I was Foreman of the Morris there for 21 years!), where I have to warn the audience that my version is different to that recorded, etc..
I do HATE it when other singers join into my songs because they "Think" they know it.
I also HATE it when the audience shouts out "Free the toast" in Rolling Home (last verse), so provided I can remember it in time I have changed the words from "let the toast go free" to "Let's toast you and me"

Tim Radford