1
When someone says 'I'm gonna do it,' they're basically saying they're going to be stupid and probably end up in the hospital or dead. It's usually because someone else told them to do something insane.
I'm gonna do it. I'm gonna eat that whole pizza by myself.
I'm gonna do it. I'm gonna jump off the roof just because he said I should.
I'm gonna do it. I'm gonna drink that whole bottle of vodka.