All of mine did, but keep in mind what the rules are.
My mother/son story was about a wrong hypnosis.
The Bondage Wife was about a woman who thought she was going to see a therapist, but it was actually something else.
The words "April Fool's" don't need to be there. And there doesn't need to be a twist. The themes of the contest are broad.
I agree. I read the rules to be sufficiently broad that the stories do not have to overtly reference April Fools' Day as long as they fit into one or more of the stated themes, which themselves are broadly drawn.
I wrote two stories but only entered one. The one I entered uses April Fools' Day as its setting, but it involves playful (and perhaps inept) deception on the part of the main characters, not an embarrassing trick played on a character by another. Embarrassing tricks are referenced, and the threat of them exists for most of the story, but they end up being peripheral to the main action.
The one I did not enter was much more mean-spirited and involved a trick that likely would have required the story be entered as a non-consent story. It did not overtly reference April Fools' Day, but it fit the 'trick' theme. I ended up not liking the story at all, so I did not enter it. Had I entered it, however, I believe it would have fallen under the rules even without mentioning April Fools' Day.