I don't speak baguette
A fancy way of saying you're too dumb to understand French and you're not even trying.
She said, 'I don't speak baguette,' when the waiter asked her if she wanted cheese with her bread.
My friend said, 'I don't speak baguette,' when he got lost in France.
He messaged me, 'I don't speak baguette, so I'm just going to scream at the restaurant.'