Characters
She over-French pronounces French words.
— Jason · Friends with Kids
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker observes that a woman pronounces French words with far more Frenchness than the words require. It's a wry, mildly mocking observation of affectation, suggesting she performs sophistication rather than simply speaking. The coined "over-French" is what makes the complaint funny.
Context reviewed