My favorite in the vicinity of etiquette and rendezvous is the "double entendre", very French sounding, but not French at all. That and something being not a person's "forte" which when correctly pronounced is just fort, but through confabulation with a musical term from Italian; forte: to play loudly, sounds more French to English speakers when mispronounced. C'est la vie.

Japanese loanwords really tickle my humour; バイト "Baito" : a casual, part-time, non-serious job. From the German "Arbeit" which is serious, macro-level employment or exertion.

Rendezvous and cliche yes. Nuance, etiquette, RSVP no. It's instinctive so I can't explain but maybe because rendezvous and cliche require using French pronounciation. On this I think you could find more differing opinions than there are possible answers.