An anecdote from my own school days which came to my mind again.
My chemistry class was just over and the pupils began spilling out of the class room followed by the chemistry teacher who was probably about to go and have something to eat as it was lunch time. The art teacher was catching up with my chemistry teacher from behind and said with a ruffled nose: “What type of experiment did you do?”
She audibly sniffed in the air to stress the point she was making.
“we didn’t do any experiments, it was just plain theory today”, replied the Chemistry teacher, “I think it’s the school meals creating the smell.”