Green’s Dictionary of Slang

extremely enthusiastic about something, really keen on or willing to do something.

[1654		E. Gayton Pleasant Notes III xi 145: When shee was in the Mubblefubbles, doe you thinke I was mad for it? no, no; I took my Asse [...] and went to the next good Town, and let it Jubble out as it Mubbled in].
1942		E. Cross The Tailor and Ansty 134: But the rest of them were soon clean mad for it.
1989		A. Higgins ‘The Bird I Fancied’ Helsingør Station and Other Departures 167: I’d drink your piss! I’m mad for it!
1996		(con. 1970) G. Moxley Danti-Dan in McGuinness The Dazzling Dark (1996) I v: Bored? Naw, Ber’s mad for it, aren’t you?
1996		(ref. to 1963) D. Healy The Bend for Home 175: One minute you’re mad for it, the next you’re not.
1999		K. Sampson Powder 94: Crowd are mad for it!
2000		J.J. Connolly Layer Cake 13: The reality as ever is that the kids are fuckin mad for it [i.e. Ecstasy], can’t get enough of it, they don’t see a problem.
2011		Times Review 30 Apr. 11/3: She progresses from being ‘mad into chardonnay’ to the ‘sauvignon blanc years’.