meh, it mine be a translation thing but I have a bunch of family that has cute nicknames for each other. Some of my cousins actually do call their littlest sister sissy so ¯_(ツ)_/¯
My entire family calls me Sis/Sissy/Sister lol it was a nickname my mom started callin' me when I was like 2 so now I'm used to it.
I started calling my older sister "sissy" last year. I started saying it after hearing the Mowry twins calling each other that. I thought it was funny and it just stuck. LOL.
I call my older sister "sissy" sometime or "sis"
Cuz its comfortable to me
I was really distract by the use of "sissy" lol, who tf calls their sister that??