Tapioca Went Sour

Saying: (When the) Tapioca Went Sour
Signifies when things started to go downhill.

Used most frequently with a strong Minnesotan accent.

My dog, Scorchy, was doing fine until the tapioca went sour. Now he is 6 feet under.

Friend Eh: "How's your day going, eh?"
Friend Beh: "It was going fine until the tapioca went sour"