I can't really think of the worst thing that has happened to me while cooking since it's a lot of random things. Maybe the fact that I burnt a lot of frozen pizzas in college but more recently I almost suffocated my roommate because I cooked spicy chicken. I basically marinated some chicken breast in olive oil, pepper, salt, and then 2x spicy hot sauce that comes in the spicy noodle package. I wanted to see if the chicken would be able to absorb the flavors. I marinated it in the fridge for a day and cooked it in a pan. As soon as the chicken hit the pan, spicy fumes started taking over the kitchen and then eventually the house.
My roommate walked into the kitchen and she started having a huge coughing fit like it wouldn't stop. Her eyes were watering and she could barely talk. I opened up the windows and doors but it still didn't help much. She coughed her way back to her room. She sealed up the bottom of her door to make sure none of the fumes got into her room. I coughed a little bit but not to her extent. I added the chicken to some shin ramyun noodles with spinach and a soft boiled egg. Did the chicken absorb the 2x spicy hot sauce? No, not really. So I almost suffocated my roommate for no reason. I mean, I got to enjoy the bowl of ramen though while she stayed in her room for a few hours.