Storytelling requires several skills including modulation of voice, selection of materials, and precision of language. Since many forms of humor depend on double meanings of words and concepts, the storyteller must choose words carefully. When expressions or idioms are difficult to translate, foreign expressions are borrowed among languages.
I was reading the book, "The Giver," by Lois Lowry with my children a couple of weeks ago. In one scene a child complains, "Im starving!" His teacher reprimands him, "Be precise. Say you are hungry. We have no starving people in our community." The teacher continues to warn all the students that precision of language is a virtue and that the adults will not tolerate imprecise language. Later in the book the readers learn the big secrets the adults are hiding from each other.
On an e-mail listserv a participant asked about the proper British expression to use at the beginning of meal that is equivalent to the French bon appetit, the German guten Appetit that is not religious. This sparked an interesting discussion. One participant, who is an English teacher living in Israel, wrote that her students frequently ask what is the English for, "btai-avon." While the teacher could translate the word to "for your appetite." The English words do not convey the same meaning as the idiomatic expressions in other languages. Some answers that received include less polite phrases such as: "Tuck in!, Grubs up! Lets enjoy our food, Get that down you, and Rub-a-dub-dub, thanks for the grub."
Saying something before we eat should have a religious connotation. Jews and non-Jews say a blessing before we eat to thank God for his partnership in the meal. The concept is that we are the ones eating and we are the ones who should be thankful. The expressions bon appetit or Btai-avon are used when you see someone else eating. For example if you serve a guest food, the guest would make a bracha (blessing), you would say Btai-avon. If you interrupt someone eating or starting to eat you would say, "Btai-avon."
Btai-avon is an interesting expression in Hebrew. The original is from the Talmud, Hullin 84a. "Shelo Yakhol adam basar ltaiavon" (One cannot eat meat except to satisfy the appetite.)
I examined Hebrew language text books to find some historical development of the expression. In textbooks of the 1940s neither expression appears. In the 1950s ltaiavon is used. In the 1980s btaiavon starts to be used. I suspect the word ltaiavon changed to btaiavon to sound more like the French bon appetite. But this answer isnt totally satisfactory. I talked to some Israelis. The ordinary non-scholars had no idea of the origins. They know when to make a bracha and when to say, btai-avon. I found one teacher who offered the explanation that the ltaiavon form indicates the appetite will be appeased in the future; while the Btai-avon form is for the present time. Linguistically this is logical
English is missing an equivalent expression. While we understand the words, "Have a hearty appetite." the idiomatic expression does not exist. One explanation offered is that the Puritans did not believe that eating could have pleasure associated with it. A story was told about a boy who once was reprimanded for complimenting his mother on her soup. The bowl was removed from his presence. The mother added pepper and forced him to eat it. Never again did the mother serve soup that wasnt overspiced or burnt. It seems difficult to believe that the Puritans could have such a strong influence on language. If they did have this influence on food related language, we should be able to find expressions that pre-date the Puritans. My ability to find these expressions is limited. The Norman conquest of English in 1066 brought many changes in the social and linguistic structure in England. The English language gained many "polite" terms from Norman French that complemented the Anglo-Saxon terms. Many foreign expressions stuck in English, because there was no previous equivalent. The expression, bon appetit, may be one of those polite borrowed expressions that just sound better in French, than, "Hearty appetite."
If you wanted your audience to "eat your words" would you tell the audience, "Enjoy!", "bon appetit", or "Btai-avon?"