we called each other …
Ci davamo già del"tu", se mi ricordo bene.
We were already on a first-name basis, if I remember correctly.
— Funny Games (1997)
As children we used to address each other informally.
— Il gattopardo (1963)
Ma non mi sembra che ci davamo del tu!
But it doesn't seem to me that we were on first name terms!
— Mosca non crede alle lacrime (1980)