Aficionados of French-Canadian swearing received a rare treat during Mad Men’s Season 5 premiere on Sunday, when Don Draper’s new wife Megan, a young Canadian “of French extraction,” reverted to her mother’s native tongue to express annoyance. She’d arranged a surprise party for Don’s 40th birthday, only to have it spoiled at the very last minute. When they came upon Roger and Jane Sterling bickering at their apartment door, and Megan realized that Don had rumbled to her plans, she let out a disappointed, “Calice.” Chances are this was American cable’s first exposure to French-Canadian profanity.

Like many other Québécois French curses, calice has its origins in Roman Catholic ritual—it’s the communion chalice. As the Economist noted last fall, Quebec has a particular history of “using religious objects as swear-words.”

The theory is that it was a form of rebelling against the Roman Catholic church, whose clergy were a dominant force in the lives of Quebeckers, providing health, social services and education, until they handed these powers over to the state following the social upheaval of the 1960s.

As a lover of both la belle province and foul language, I always keep a copy of Canadian French for Better Travel to hand. Consequently, I hereby predict that in the next 12 weeks we might hear Megan use one of the following expressions of annoyance and frustration: Calvaire! (Calvary), Ciboire! (ciborium—the container in which communion wafers are stored), Ostie! (communion wafer), or Tabarnak! (tabernacle—the case in which the wafers and communion wine are stored).

If her workload at Sterling Cooper Draper Pryce doesn’t lighten up, we might even hear Megan make this very Québécois declaration (in Canadian French for Better Travel’s version of French-Canadian pronunciation): “Chu dans marde jusqu’au cou.” Or as Peggy might put it: “I’m up to my neck in merde.”