Mad Keen
When you call someone mad keen, you're saying they're so excited they might lose their mind or start a fight.
Bro, you're mad keen on this pizza, I swear you're gonna eat the whole thing and then throw the box at me.
She's mad keen on this party, she showed up 2 hours early and brought a bottle of whiskey.
He's mad keen on this fight, he challenged the guy who just walked in, even though he's got a broken arm.