For companies (not for people), the term "take it out of petty cash" could be used.
Petty (from the French, "petit", small) cash is designed to be "effectively ignorable money that can be used for stuff that costs less than the internal cost of expensing it". Donuts for a meeting; a box of pens; that sort of thing.
Now big companies - especially big companies in the financial sector like Goldman Sachs - tend to actually be more "rule-bound" about tiny expenses than many small companies. Partly it's a "you can't be blamed if you follow the rules even when they're stupid, but you absolutely can be blamed if you don't, even if you save money"; partly it's the fact that they're under significantly more onerous and more powerful auditing régimes ("failed SEC audit" is a heart-stopping phrase on Wall Street); and partly it's because petty cash embezzlement and reporting fraud has in the past been common, and can add up quickly. But the idiom still exists.