Don't let this keep you from occupying Wall Street, because banks are still awful, but Citi helpfully lent its data to reveal the true cost of eating at expensive restaurants. Finance blogger Felix Salmon dove into anonymized credit card slips and found that people fling money around as unpredictably as wild monkeys in these places.

Using data from Citi-backed web startup Bundle, Salmon plotted various nifty charts (like the one above) showing spending patterns and tried to make sense of them. He was unable to! He ran all sorts of calculations — median, mean, mode for various restaurants — and did find Citi's data a vast improvement over Zagat/Google's impossibly low estimates. But in the end, there's no guessing what we'll do when eating out. We're basically animals:

The range of expenditures at Megu is enormous... A diner at Babbo has a pretty good chance of coming up just about anywhere between $60 and $270... At Mr. Chow's ... Bundle says the "real price range" is $210 to $220. The median amount charged to a card there is actually $145. And 2.1 percent of customers spend more than $800, while 17 percent spend less than $70... Customer spending in New York is all over the place.

In a companion piece at Reuters, Salmon concludes, "the big picture is that the differences between restaurants pale in comparison to the differences between diners. Some people are just going to spend a lot, others are going to get away with spending much less."

So take from this tiny slice of financial sector data a small lesson in sticking it to the banks: Order less, and you avoid borrowing from the likes of Citi, or enriching them with transaction percentages. Better still, just pay in cash. (Or as they call it in the fancier places, "Heritage Tender.")

[Pic: Per Se via Getty Images. Chart via Grub Street.]