I think we tend to seriously underestimate the French. (Oh, drat, I split another infinitive!) Here are a few expressions that you might find interesting.
Faire avancer le Schmilblick
That strange word means nothing more or less than “thing.” When having a conversation, comments not deemed to be helpful are described as not advancing the Schmilblick along. If you speak excellent French, here is a YouTube video describing the origin of the term.
C’est le petit Jésus en culotte de velours
You’ve just had an incredibly smooth wine. It was, in other words, “as smooth as Baby Jesus in velvet knickerbockers.” (You can’t say that about an American beer.)
Avoir le cul bordé de nouilles
You are incredibly lucky—such that your ass is surrounded by noodles.
Il pète plus haut que son cul (ou tête)
There are two variants to this one, both describing someone who is incredibly pretentious. The way Martine and her mother described it, “He tries to fart higher than his own head.” Others say “higher than his own ass.” Perhaps Martine’s version is the way they say it in Normandy.