gu gu bro in chineses jie jie sister in chineses

It's ge ge 哥哥 。
Edit: ge ge and jie jie means can be different (which is darling/handsome/beautiful) if it is being used by your partner or spouse.

so u have to be careful how u pronounce it one way can be harmful

Yup, literally!😂
Because gu gu (姑姑) means Aunt🤣.

noooooo i made a mistakeeeeeeeeeeeeeeeeeeeeeeeeeee

Pronunciation for ge ge and jie jie is same, no matter if u r using it as brother or as darling. Meaning depends weather who is calling you ge ge or jie jie.
Most of the time, Chinese people use terms like 大哥 da ge (Elder Brother)/弟弟 di di (Younger Brother) or 妹妹 mei mei (Younger Sister)/大姐 da jie (Elder Sister).
Previously, Chinese people also used these terms as well such as 一哥 yi ge (Fist Brother)/二哥 er ge (Second Brother)/三个 san ge (Second Brother) or 一姐 yi jie (First Sister)/二姐 er jie (Second Sister)/三姐 san jie (Third Sister) and up to so on.

Thanks for the info!!

No problem. Any time✌.