Fig.: to talk nonsense

Don't listen to Julia. She's just talking through her hat, as usual

Non prestare attenzione a Giulia, lo sai che parla sempre a vanvera

Don't you realize you're talking through your hat? You don't know the subject and you're talking nonsense

Non vedi che stai parlando a vanvera? Non conosci l'argomento e dici solo sciocchezze

She claims to work as a cleaning lady for fun, but she's actually loaded. To me she's just talking through her hat, and I don't buy it for a second!

Dice di fare la donna delle pulizie per divertimento perché in realtà è straricca. Per me, dice solo fesserie e non le credo neanche morta!

The use of this expression dates from the late 19th century, but its origin is uncertain. It is said to be from the deceptive conduct of men who hold their hats over their faces on entering church, and are supposed to be praying