On a recent trip between country towns I was stopped for a Breathalyser check.
Usual procedure, count to 10 into the device.
Deciding to be smart l counted
“Un, deux, trois- - -and up to ten in French.
The Constable checked the reading, then straight faced, said
“Merci M’seur”
Then with a smile bade me have a good day, also in French.

Served me right, but at least I got a good joke, even if on myself.