Idiot In Chinese

白痴 《—— Bai (second tone) Chi (First Tone, but actually sounds more like tzi, buuuut chinese is hard for a reason so if you wanna type this phrase, the pinyin is bai chi) also, BTW this phrase is actually pretty offensive, so it's not like, okay, ur dumb, only use this when talking to yourself or when you're talking to close family and/or friends and you don't mind getting slapped. (unless that is, the person doesn't understand chinese, you can say it whenever)

For the example of use for idiot in Chinese, you can use it when ever you would normally use the word "idiot" in english.