French Déformation professionnelleA quirk, trait or habit caused by one's occupation.

A cashier absentmindedly checking the bills they got from the ATM for counterfeits, a firefighter mentally taking note of where the emergency exits are when visiting a new business, an archivist turning the pages of the novel they're reading very gently - these are all examples of a *déformation professionnelle*. A call center employee answering their phone with a rote "Hi, my name is Kevin, how can I help you today?" may also be considered a kind of *déformation professionnelle*, but the phrase usually implies professional know-how seeping into one's private life rather than simple muscle memory or canned phrases.