I was visiting my mom one holiday and noticed that she had some chocolate ice cream and some marshmallow topping in the fridge. Later, after I had smoked a bowl, I headed to the kitchen, loaded up a bowl of ice cream and proceeded to cover it with the marshmallow topping. As I'm spooning it on, I notice that the consistency is very thick for marshmallow. Finally, after my ice cream was thoroughly covered, I realized that is was not the marshmallow that I had grabbed from the fridge... it was mayonnaise. :/
Fortunately, I realized before eating any, but yeah - whole bowl of ice cream down the drain.