Like a puddin'

I heard this today and it boggles my mind:

The proof of the pudding is in the eating.

Edit: So my friend Cindy pointed out that the incorrect saying is "The proof is in the pudding." - this is actually a legitimate saying! So I have to retract this one, since it is not a mixed metaphor.

But I will just add this: The proof of the pudding is eating a horse.
(This isn't too far off, since gelatin is made from hooves and bones.)