tosta/u
Stubborn, hard-headed, strong-willed in Western Sicilian dialect. Used to refer to toddlers, or young children who are sassy and cutely resistant, but said with pride and awe on the part of older relatives. Phonetically it sometimes sounds like "thoistu" for a boy, or "thoista" for a girl. Others will pronounce it closer to "thosta" or "thostu".

The elder relatives may in one sense disapprove of the behavior, but yet be satisfied that the child is demonstrating free spiritedness and self- initiative. The expectation is that these kids will not be easily influenced by their peers and learn how to stand up for themselves.

To have heard this in your household your grandparents, parents, or aunts or uncles would have had to be exposed to turn of the century (1900) western Sicilian dialect, even if you heard it in the second half of the twentieth century. 1950 to 2000. It is becoming more and more rare to hear it.
A nonna looks at her four year old grandson as he is about to write on the wall with crayons and he boldly keeps doing it even as his parents firmly say "NO!" So the nonna smiles and says:

"Oh! He is so tosta/u". Similar to "boys will be boys".

A little girl throws her stuffed animal at her cousin who is visiting and her mother, partly embarrassed, but partly amazed, will grin a bit and say:

"I'm sorry, but she is just so tosta/u"

But the child is still gently discouraged from the behavior, but the parent is glad the child can protect themselves if necessary.