Student or Learner
How to call this kind of money?
Usually husband put some money (perhaps, big amount ) into the secret place without knowing his wife.
A: Hey, letís have a beer tonight, Iíll buy.
B: Where did you get the money from?
I donít think your wife gave you $ for beer?
Let me buy it.
A: ⓐI have some secret money, donít worry. ⓑI have some secret purse, don't worry.
Thanks ~ Anglika
Can I ask one more thing?
Can I say like this? ...
A: Hey, do you have some money put by in a stash? I need about $700?
B: Sorry I had some but I was found by my wife and she took all of them.
Sometimes some money put by is referred to as 'under the mattress' (even if that's not where it really is): 'These days I'd rather keep my money under the mattress than put it in a bank.' But in the case you've been discussing with Anglika, just 'put by' is better.