Jim, I was being facetious.
I know, it's hard to tell in print.

I don't have any trouble getting my audiences to sing along, or not, depending on the song.
If I want them to join in, I'll encourage them to do so, and if I don't want them to join in, I'll say something along the lines of: 'Listen to the words of this one."

I find that a bit more diplomatic than saying: "Now, don't sing along with this song."

And occasionally it's fun to try to get them to sing along with an instrumental piece like Dueling Banjos or the Teetotaller's Reel.

Really!

Seamus