kaathi
A person who acts like a saint one moment and then throws a tantrum so loud it wakes up the neighbors.
My sister is a kaathi. She hugged me when I came home. Then she yelled at me for eating her chips.
My neighbor is a kaathi. She said 'Great job!' at the party. Then she sent me a 300-word rant about the music.
My brother is a kaathi. He said he'd help me clean my room. Then he left and played video games all day.