my roommate (the last three years) was a math tutor my senior year, the same year we shared an apartment off campus. One of her fellow tutors was an amazing cook...but unbeknownst to us, he was one of those people who would deliberately leave out ingredients if he gave you a recipe. Now I hate that...either give out the recipe exactly as you make it or politely decline to share the recipe ("I'm sorry...it's a family secret!").
So one afternoon, roomie decides she's going to make a chocolate cheesecake for a gathering she was having later that night. The recipe is from jerk tutor who leaves out ingredients, but again, we didn't know that at the time. So she's in the kitchen a few hours before the gathering, cooking up a storm, and she mixes the batter for the cheesecake. She then asks me if I want to lick the spoon (I did not then, nor do I now, particularly worry about eating batter with raw eggs in it, though I wouldn't eat a large amount of raw batter). I say sure, grab the spoon from her, take a biiiiiig lick...and nearly spit the batter out. It was completely without sugar of ANY kind. Now I'm not a frequent baker but Mom used to make Grandma's sour cream cheesecake all the time, and I often would help (and would later cook it by myself; for years, it was tradition to make the cheesecake, which is made in a 9x12 pan, not a springform pan, and then use blueberries and sliced strawberries to decorate it to look like a flag before taking it to my aunt and uncle's 4th of July party). I scan the recipe...jerk tutor left out the sugar. Roomie calls jerk tutor who grudgingly tells her she needs x amount of sugar AND sweetened condensed milk, and of course we have no condensed milk in the cupboard. What college kid keeps condensed milk in their kitchen? So I practically (literally) ran to the grocery store about a quarter mile from our apartment, bought the condensed milk and practically ran back. The cheesecake was finished just in time for the guests to arrive, and it was delicious...once the sweetness was added to the batter.