Affectionate Gesture to the Head: In "Vote for Casper" Mantha strokes Casper's head when she reveals that she did vote for him. In "What Possessed You?" Stretch also strokes Casper on the head when he believes Casper gave up on being friendly.
Berserk Button: Unsurprisingly, he doesn't react too well to his friends being threateaned.
In "What Possessed You?" he scarred one of the Normans after he possessed Casper and bullied his classmates and Jimmy.
In "Messy Bussiness at the Manor", Mosshead found out about Casper being friends with a fleshie and intended to tell everyone at Scare School. Casper finally snaps and chews him out for being an Ungrateful Bastard. He insults Mosshead and unintentionally scares him.
Don't you ever embarrass him in front of his classmates.
Our Zombies Are Different: She is actually smart and agile. The walking slowly while chanting "Braaains..." routine is just a scare tactic zombies use. And though she does eat brains, it's not all she eats.
Pink Means Feminine: Subverted. She wears a pink shirt and her shoes have pink shoelaces but she's rather tomboyish.
Small Name, Big Ego: Played with. His ego shows in that he forces Alder and Dash to sing him songs thanking him for not insulting or hurting them. Given his status as king of all ghosts and ruler of the Underworld though, the "small name" part does not really hold up.
The Dreaded: To all humans and creatures (except Casper).
Would Hurt a Child: Played with. He was never seen hurting a student. However, he has made things that would have hurt or even killed the students in season 1, plus Alder and Dash implied that Kibosh gives the students the same hideous punishments he gives to adult creatures, although Kibosh believes he is doing what's best for his people.