In a previous life I was one who had to be prepared for my in-flight service before take-off. I preloaded the cory pots with tea bags and coffee.
Got in the air and loaded them again somehow forgetting that I had already preloaded them and managed to add a coffee mix to the cory pot with tea bags in.
Proceeded to serve the pax with this coffee/tea mix and heard people spitting back their hot drink into their cups. I was so embarassed. Had to apologise to each passenger individually and go through the cabin collecting their COFF-TEA mocktail !