Speaking of Wagner....
I went to see Die Walkure in San Francisco years ago. It took all of my energy not to sing "Kill da wabbit. Kill da wabbit. Kill da wabbit." During the big number. I'm pretty sure I wasn't the only one.
Somehow I think your friends at the Indian restaurant wouldn't have found it so funny.
(Here's a link for anyone who doesn't get the reference)
https://www.youtube.com/watch?v=wGhQ2BDt4VE