mad c
A mad c is a person who either does something so amazing it makes you want to cry or something so stupid it makes you want to punch them. Either way, you're stuck with them.
You: "He just won the lottery." Me: "That's a mad c."
You: "She tried to talk to a dog and it bit her." Me: "That's a mad c."
You: "He tried to eat a whole cake in one go." Me: "That's a mad c."