I'm not adding context to the joke, I'm pointing out that people are misinterpreting the dialog as it was written. by saying "I don't know what the additional context is", I was saying "perhaps she had just said TGIF!" and that would explain why he said "it's Wednesday"

"What a week, thank god it's over!"

"it's wednesday"

would work for your lowest common denominator.

But that’s NOT the joke. There’s no implication the week is over on her part. It’s more “so much has happened it feels like a week” much more than “thank god it’s over”

Saying “a week full of mondays” doesn’t mean it’s over either.