“Yes, I have that muffin you didn’t tell me was already two days past its expiration, and it’s already working its way through my digestive system.”
EDIT: Since this question was put on hold for being too vague, let me try to narrow down my concerns.
I assume there’s something quite wrong with the construction as to this part, you didn’t tell me was already two days past its expiration, though I cannot seem to pinpoint what it is (supposing there is an error).
Also, the sentence is intended to be satirical. So you don’t have to worry much about semantics. It’s the grammaticality I’m concerned about.