a mad ting - A mad ting is a mad ting. It’s like saying 'Hello' is 'Hello

A mad ting is a mad ting. It’s like saying 'Hello' is 'Hello.' It’s a thing that’s so good or so weird it needs to be called a mad ting.

'That ting is so good, it’s a mad ting!'

'That’s so weird, it’s a mad ting!'

'He just started talking to the cat. That’s a mad ting!'