Quoting Angel's (Army) Wifey:" Brother and Sister mostly they aren't very creative. Lol Sometimes they will use mommy and daddy's nicknames for them Catalina is Kit Kat and Thomas is Tom Tom."
Quoting Irish Mammy*J,R&A*:" My kids use my nicknames for each other sometimes too. They will sometimes call my daughter houdini, I call her that because shes always escaping lol"
Quoting Irish Mammy*J,R&A*:" What nicknames do your kids have for each other? Been given by other kids? My daughter Aoife gets called ... [snip!] ... haha My five year old has recently started referring to his little brother as smurfbag which im clearly trying to stop! lol"