blot your copybook

US /blɑt yər ˈkɑp.i.bʊk/
UK /blɑt yər ˈkɑp.i.bʊk/
"blot your copybook" picture
1.

merusak reputasi, mencoreng nama baik

to do something that spoils your good reputation or record

:
He was a promising student, but he blotted his copybook by cheating on the final exam.
Dia adalah siswa yang menjanjikan, tetapi dia merusak reputasinya dengan menyontek di ujian akhir.
One mistake could blot your copybook for years to come.
Satu kesalahan bisa merusak reputasimu selama bertahun-tahun yang akan datang.