mad dog keen
Being so hyped about something you're ready to do anything, like fight, drink, or ride a wave even if it's got a face.
"I'm mad dog keen, I'll take on the whole bar if I have to."
He was mad dog keen, so he drank the whole bottle of wine and then started singing off-key.
She was mad dog keen, so she jumped into a fight even though she didn't know how to punch.