Professor Tact from Luxembourg University published his findings today.
"It's fascinating!" he chirped. "Attempts at all other languages are met with frowns, shrugs, back slaps and people smiling because you made an effort."
"But when a non-French speaker drops two French words in a row, that's it! Something clicks, very much like a mousetrap. There's no going back. It's a drop of blood in the ocean to a shark 500 miles away."
Legal Secretary and study subject Eliza Hrusku explained, "One day I added 'ca va' to my 'bonjour' and now its just non-stop French all day long."
Professor Tact is now deep into his next study, getting to the bottom of the two-and-a-half hour lunch break ; and just how the same people are sick for one week before and after a two week holiday.