Such an expression is mad money, noted as early as 1922 by Howard J. Savage (Dialect Notes 5:148) at the end of an article on Bryn Mawr slang. Savage's definition is 'money a girl carries in case she has a row with her escort and wishes to go home alone.'.
Ultrasuede minibags are just the solution for waste. And for crime. Most minis hardly hold more than mad money and a comb.