Actually, I don’t believe either of these count as lie–more like things I didn’t tell my students because it was better that they not know.
Many years ago, when I was really young and taught Spanish at Hays High School in Western Kansas, I took 25 of my students to Mexico in a bus. We stayed two weeks. At one of the first restaurants we dined at in Mexico, I was talking to the manager about payments, etc. I gotto the dining room after most of the students has finished their soup. I sat down, looked into my bowl and noticed that there were tiny worms in the soup, wiggling in and out of the chunks of chicken. I felt nothing would be gained if I shouted, “You all ate soup with worms in it.” So I stopped eating and pretended this never happened. Fortunately, no one got sick.
Before the celebration of el día de los muertos, we made crafts that Mexicans would have
used for decorations. A popular craft is to decorate sugar skulls. I decided to use this with the 4th and 5th year Spanish students. Because the skulls were sugar, I broke up a chipped skull–they were a little smaller than a fist–and passed the pieces out to the fifteen students to sample. They tasted like sweet, thin cardboard. After two days, we finsihed the decoration and painting. As I was putting the material back, I read the side of the box that contained the skull. There was a warning on the side: These skulls are not meant for human consumption.
I never told them this either. No one died.