I was finishing a jar of extremely hot peppers (7 pot primos) that I had fermenting on Thanksgiving day. I made a hot sauce with them and cantaloupe. I had them in a pan at a low simmer to meld the flavors. The problem was the steam coming off was potent as hell. It filled the house when everyone was arriving and coughing from the hot sauce in the air, me included. We had to open all the windows, dig out the fans to get it out of the house, freezing everyone in the process.
This was not actually my mistake, but last year we bought an expensive fresh turkey two days before Christmas, and unbeknownst to me, my husband decided to store it in the oven (mistake #1) then my son turned on the oven to cook something else, causing the turkey's plastic bag to melt to the turkey (mistake #2).
Once I learned that the thing had been unrefrigerated overnight, it was no longer going into my mouth. My husband was hoping I'd rethink that, so I was actually pleased when the melted plastic made it inedible even by his very lax standards.