the joke is on someone
US /ðə dʒoʊk ɪz ɑn ˈsʌmˌwʌn/
UK /ðə dʒoʊk ɪz ɑn ˈsʌmˌwʌn/

1.
lelucon itu kembali pada seseorang, seseorang menjadi bahan tertawaan
used to say that someone who has tried to make another person look silly has in fact been made to look silly themselves
:
•
He thought he was being clever by tricking me, but the joke is on him now that I've exposed his lies.
Dia pikir dia pintar dengan menipuku, tapi lelucon itu kembali padanya sekarang setelah aku membongkar kebohongannya.
•
They tried to embarrass her with a prank, but when it backfired, the joke was on them.
Mereka mencoba mempermalukannya dengan lelucon, tetapi ketika itu menjadi bumerang, lelucon itu kembali pada mereka.