We don't sell cheese.

Chi is a brand of hair dryer/flat iron and hair products.  The brand's got a large share of the flat iron market, so much so that a lot of people refer to flat irons as Chi's.

One day, a customer walks in and asks Bianca, our truly wonderful front desk person at the time, "Do you sell Chi's?"

Bianca gives her this puzzled look, pauses and says, "No, but the liquor store next door might have some."   Then it's the customer's turn with the puzzled look.  The customer left.  I have no idea if she went to the liquor store looking for a flat iron or not, but the infamous Cheese incident was good for a lot of laughs once people figured out what had happened.  I think Bianca laughed hardest.