When you leave a piece of hot toast on a surface and it leaves condensation. Explained in Fraiser, episode 24 "My coffee with Niles"
Martin: By the way you left a mess in the kitchen.
Frasier: I had a piece of toast!
Martin: Yeah, and you didn't use a plate like I asked you too, and you put it in under the counter. And all because you left a bunch a crumbs and toast sweat there!
Niles: Toast sweat?
Frasier: Yes, yes, it's when you put a piece of hot toast on any surface, and it leaves droplets of dew behind. Haven't you heard dad's lecture on the evils of toast sweat? It's the scourge of our times.
Frasier: I had a piece of toast!
Martin: Yeah, and you didn't use a plate like I asked you too, and you put it in under the counter. And all because you left a bunch a crumbs and toast sweat there!
Niles: Toast sweat?
Frasier: Yes, yes, it's when you put a piece of hot toast on any surface, and it leaves droplets of dew behind. Haven't you heard dad's lecture on the evils of toast sweat? It's the scourge of our times.
by Exploding_Carrots February 29, 2008
n, a noun used to describe the condensation left on the plate when you lift a slice of hot toast off the plate.
Daniel: "My plates covered in toast sweat."
Jo: "Don't worry about it, your toast will be finished in a minute."
Jo: "Don't worry about it, your toast will be finished in a minute."
by The Fairy Sesh Mother February 28, 2021
by Jake Stowell April 07, 2006