Bring on "the sharks they played melodeons".
Not the only part of that song that gets messed about!

As for certain actions done during "Wild Mountain Thyme" in some quarters......a panting sheepdog, Lassie, And so on......

And the more recent song to have odd interjections introduced into it is Keith Marsden's "Funeral Song" - when it gets to the line about "they had to send for extra chairs", people start piling up all the chairs in the room, more each time the chorus comes around, until there is a very unsteady monument of them! How disrespectful! ;-)