the joke is on someone

the joke is on someone

If you say that the joke is on a particular person, you mean that they have been made to look foolish, especially when their intention was to make someone else seem foolish. It didn't take long before we began to feel that maybe the joke was on us. Well kids, the joke is on us. We thought we were going to keep a secret from Nancy, but she's way ahead of us.
See also: joke, on

the joke is on someone

someone looks foolish, especially after trying to make someone else look so. informal
1998 Spectator He turned out to be as right as rain…so the joke was on us.
See also: joke, on