The first time I made brisket (my MIL's recipe) for my in-laws shortly after we were married.
I had never cooked brisket (or any kind of roast) before in my life. (I grew up with my mom stir-frying everything) The directions said to cook one hour per pound. I never wrote down when I put it in the oven and after what seemed like hours, I checked the meat. It seemed cooked through, but tough -- so I took it out (thinking, wrongly, that it would only get tougher if I cooked it longer). We had my in-laws for dinner that night. They were real troopers. When I asked my father-in-law if he would care for any more -- he replied,"no thank you. The flavor was great, but my jaw is tired from all that chewing." It was another two years before I tried to make brisket again!
To make me feel better, my MIL (who is a great cook) told me the first time she made lasagna -- shortly after she was married -- she assembled it without ever cooking the noodles. My father in law calls it the "crunchy lasagna" episode.