They do it just to annoy, you know.

The other week I was making sandwiches for the nieces for lunch, because I had some turkey to use up before it went bad and I thought it would be good if they had a lunch other than eggs one day that week.

Now, for the past year, approximately twice a week, I've been making them meat sandwiches with mustard, because they both professed a profound dislike of mayo. I mean, "hide the lunch behind the sofa" levels of dislike. Never mind that the huge jar of mayo I bought before they expressed this dislike slowly expired and went bad in the fridge, it was mustard all the way! So, of course, what was I doing to these turkey sandwiches?

I had just spread the mustard on two slices of bread when Evangeline walked in and said "Oh, I don't really like mustard anymore. I want mayonnaise."

Me: The same mayonnaise you've refused to eat for the past year?
Eva: Yes. I mean, I'll eat it, because you already made it and I know Ana likes it, but next time, can I have it without the mustard?
Me: Sure. So long as you tell me in advance, it's not a problem.

Eva leaves, and right on cue her sister walks in!

Ana: Ew, mustard. Can't you make it with mayonnaise for once?