the joke's on (one)

the joke's on (one)

1. One is experiencing or will experience a negative outcome, particularly one that was intended for someone else. The phrase typically refers to a practical joke or malicious act that has backfired. Greg set up this bucket of water to fall on me, but the joke's on him now—I rigged it up over his bedroom door. He thought he could steal my job by telling the boss terrible things about me, but the joke's on him—he's getting fired for misuse of company time.
2. One seems silly or foolish. Well, the joke's on me because I spent so much time perfecting our itinerary that I forgot to put gas in my car before the trip.
See also: on
Farlex Dictionary of Idioms.

joke is on someone

 
1. Someone is the butt of the joke. The joke is on Bob, so it's good that he is a good sport.
2. The joke has backfired on someone. Ha, ha! The joke's on you after all.
See also: joke, on
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

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, someone
Collins COBUILD Idioms Dictionary, 3rd ed.

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, someone
Farlex Partner Idioms Dictionary

the joke’s on ˈsb

(informal) used to say that somebody who tried to make another person look ridiculous now looks ridiculous instead
See also: on, Sb
Farlex Partner Idioms Dictionary
See also:
  • get a taste of (one's) own medicine
  • drive (one) out of office
  • force (one) out of office
  • force out of office
  • give (one) (one's) head
  • give head
  • give somebody their head
  • give someone their head
  • cooking for one
  • 1FTR