What looks like food, tastes like food, smells like food, sounds like food when you cook it, is grown in dirt like food, fills up your stomach like food, but is not food?
A poisonous mushroom. Since some types of mushrooms are edible, it can be very hard to distinguish between a safe mushroom and one that will kill you. Food is defined as a substance consumed to provide nutrition, therefore a poisonous mushroom that kills you doesn’t qualify as food, even though it shares all of the traits of a regular mushroom.
Other valid answers include anything that’s edible, resembles food, but is poisonous.
Ralph goes to the hardware store to buy something for his house. He asks the clerk how much one will cost and the clerk looks it up and tells him it will be $3. He asks about buying twelve and is told it will be $6. Two hundred will cost $9.
Fish. The gh is pronounced as in tough, the o as in women and the ti as in nation. Ghoti is a constructed word to illustrate irregularities in English spelling.
The letter ‘X’. A single x is often used in math as an unknown, along with Mr. X. Two together (XX) make the Roman numeral 20, and three signifies a warning for adult only content, or a warning to other programmers of a problem in source code.