non so che dire

I don't know what to say

→ non
phrase Rare #25,468
I don't know what to say A common expression used when someone is surprised, embarrassed, shocked, or unsure how to respond. The verb can change with the subject or tense, as in non sapevo che dire (I didn't know what to say).
IT: Dopo aver sentito la notizia, non so che dire.
EN: After hearing the news, I don't know what to say.

Non so che dire, mi hai appena chiamato Diavolo.

I don't know what to say—you just called me Devil.

— Goksung - La presenza del diavolo (2016)

Non so che dire.

I don't know what to say.

— I Tenenbaum (2001)

Semplicemente non so che dire.

I simply don't know what to say.

Non so che dire, signora.

I don't know what to say, ma'am.

— Agora (2009)

Papà, non so che dire.

Dad, I don't know what to say.

— Ratatouille (2007)

Goffredo, non so che dire.

Goffredo, I don't know what to say.

— I visitatori (1993)