I managed to wreck a very atmospheric rendition of my setting of "The Lady of Shalott" once by mentioning in my intro that I'd noticed the first reference to fast food towards the end of the ballad. It's over eight minutes long, and the audience were with me every step of the way, until I reached the crucial line
"Out upon the wharves they came
Knight and burgher, lord and dame"

I've learnt now not to say anything about it until the song is over ...

Anne