When I was growing up, we called my parents' best friends Uncle and Aunt. Also, my husband's first cousins are very close with our family and we get together often in large family gatherings. My children call them Uncle and Aunt and their kids call us the same. We all talked about it after the first children of that generation were born and it just seemed less confusing for the children to all call each other cousins but all the adults Aunt and Uncle.
