When I worked at Walmart, bananas were the number one selling item at $.68/pound. Then, for a week, someone set the price to $.68/banana. So a whole bunch went from like a dollar and some change to like $7 on average. Instantly killed the sales until they went back to per pound. When I was asked to change the price sign, I asked if it was a mistake and they told me no.
Fun fact: At least here in Germany, supermarkets almost lose money on bananas. They can't raise the prices because the price of bananas is so ingrained into people's minds that an increase would implicitly signal "expensive store" even if all the other prices stayed the same.