Teaching a teacher a lesson

Two female teachers at a high school had a routine of sharing their coffee and snacks together during their morning break in the teacher's room. Each would bring a favorite snack and it would be shared between them.

The problem was a male teacher who would pass by while the ladies were taking their morning break. He would see the spread on the table and utter something like, "Wow, cookies!".

Then he would help himself without an invitation and would keep taking one snack after the other. This habit of his really irritated the two lady teachers as the male teacher never had the decency to offer anything nor had he ever asked if he could help himself.

Finally the lady teachers decided enough was enough, and they came up with a plan. One of them bought a doughnut, took out the custard and substituted it with mustard. When the male teacher came in the teacher's room that day, he helped himself to the only doughnut left on the plate as was his habit and left. He never said anything about the mustard, but never went to the teacher's room again when the female teachers were taking their snack break.