behind my back
You did it behind my back.
No me gusta cuando la gente habla de mi a mis espaldas.
I don't like it when people talk about me behind my back.
Siempre hablan mal de mí a mis espaldas.
They always talk badly about me behind my back.
Entonces oí la puerta abrirse a mis espaldas.
Then I heard the door open behind me.
— Pacto de sangre (1944)
Averigüé que hablas a mis espaldas.
I found out you talk behind my back.
A pesar del hecho de que todos se ríen de mí a mis espaldas.
Despite the fact that everyone laughs at me behind my back.
— Juno: Crecer, correr y tropezar (2007)
Don't say it behind my back.
Te has reído de mí a mis espaldas.
You laughed at me behind my back.