They were watching the Grey's Anatomy big wedding finale. Izzie was berating Shepherd about writing his vows for Meredith and told him that it was very important because his future wife would remember what he said for the rest of her life.
She said: "I have no memory of what we said to each other on our wedding day!"
He said: "I remember. I'm sure you said you'd obey."
She laughed till she cried.
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