Entremets.

Most of us heard the children's nursery rhyme with the lines

"Four and twenty blackbirds, baked in a pie
When the pie was opened, the birds began to sing
Now wasn't that a dainty gift to set before the king?"

As a child, it seemed like hilarious nonsense.
As I grew up, I assumed it was some sort of allegory.

Last night, I remembered it again, and got curious. It turns out these lyrics are literal and refer to a real thing. Living birds were often hidden inside courses of high-end fancy dinners to be revealed as entertainment. Guests, presumably already a bit drunk off the wine, would laugh uproariously when the chef or a guest cut open a pie and caused a flock of birds to fly out.

The practice was called an "entremet" and you can learn more about it here: