Now That's Proliferation

An informal web search just turned up 14,600 results for a common catchphrase, and as far as I could tell, not one of them led to the actual, original, intended application of the saying.

So many of our shared references are just these peculiar bastard things, now, these things we say to be cute - charmingly reassigning an established idea, as it were, and yet we really don't even know what we're mocking.

When, say, your dog prods your cat with his nose, and the cat responds by rearing up on his hind legs and boxing the dog in the snout with his fuzzy little paws, you watch, and laugh, and quip: "Now *that's* entertainment!"

And it is, and everyone else laughs too. But what, I ask you, originally "was" entertainment? When the first person said those words, the only one who wasn't trying to be sly or clever or knowing or any of that, what was he or she actually referring to?

And how did it get lost to history?