“Excuse my French!”
An idiom is a phrase that means something completely different from the literal meaning of its individual words. Idioms give languages colour, making them rich and beautiful!
It is often difficult to understand an idiom just by thinking about the meaning of the individual words and for that reason non-native speakers find it difficult to use them. Often students don’t start using idioms until their English has reached a relatively advanced level. However, when students with an intermediate or even basic level of English learn a few idioms and start using them, their English immediately starts to sound more sophisticated and natural.
One humorous example is to say, “Excuse my French!” when using swear words. The humour comes from the fact that both the speaker and the listener know perfectly well that the offensive language is English, not French! The expression, which is particularly funny when used by a French person speaking English, was first used in the 19th century. People would throw in the odd French expression while speaking English, which they would apologise for by saying, “Excuse my French!”