What would make you feel embarrassed in public?
It took me a while to think of something that would really, truly embarrass me, but I'd have to say something like having my credit card declined. Even if it was no fault of mine, like their system was malfunctioning or something, I'd be very ashamed of that. I take pride on my ability to juggle our money - I mean, we bought a house, for crissake, with barely enough money to put up for the meager 3.5% down payment on our crack house. To have someone, even just one person, think that I'd lost control of something as important to one's daily life as our finances.
I have a coworker who says that if you're not willing to have all of your money pooled together with your spouse, you don't trust them enough to be married. Jeff and I have a joint account, because you apparently have to in order to get a married-filing-jointly tax return direct deposited. Other than that, though, we don't pool our money.
Between my parents, my dad earns about 75% of their income, my mother 25%, but I spent my childhood watching my mother spend money. And spend money. And spend money. I'm not saying that they shouldn't have pooled assets or anything, but when you spend and spend into credit-card-debt-oblivion, and leave the primary earner to figure out how to pay down $100,000 in debt... that stayed with me. Thankfully this agreement works for Jeff.
Somehow I think I deviated from the prompt a bit, but I have a feeling that's the point.