King is wearing a pink shirt today for Pink Shirt Day, organised by the Mental Health Foundation and other agencies to stand up against bullies and show public support for their victims.
The day began in Canada in 2007, when a group of students stood up to defend a student who was bullied because he was wearing a pink shirt. They all wore pink shirts to show solidarity with him.
Many primary schools are encouraging all their students to wear pink today. Some colleges, such as Auckland's Green Bay High School, are holding mufti days so students can wear pink instead of school uniforms.
King said he had been both a victim of bullying and a bully himself. As a professional comedian, he used to pick on people in the audience who were not laughing at his jokes.
"I'd see the person in the audience who I believe doesn't like me, and your immediate thought isn't anger, it's hurt. 'Why don't you like me?'," he said.
"Because you are feeling hurt and waiting for them to jump on you and hurt you, your first thought is to hurt them first.
"So the next thing is I find myself on stage bullying someone in the audience and mocking them in front of everyone."
It took him years of sessions with a psychologist to realise that he felt insecure because, as a child growing up, he was always looking for his father's approval.
"This is a problem for a lot of boys," he said.
"My dad always loved me, but he was from the old school and they didn't hand out praise, so I had this unsatisfied need for my old man to pat me on the head.
"So I became a needy person: 'Maybe I'm not good enough'. As I grew up, I covered it up with this overconfident exterior."
Like most bullies, he said, he didn't realise how much his words hurt other people.
"I believe that if these people realised the impact they were having, they would be the first ones to put their hand up and say, 'Hey, I'm being a dickhead and I have to stop'."
"My mother always said: 'If you have nothing nice to say, son, say nothing at all'."
