When I was young and making $9 working at Gamestop, I banked with First Tennessee. I'm pretty sure this is illegal now, but they would let all of your transactions build up for a week or more and then put them in from largest to smallest. So, say I bought a $2 coffee on Monday and then paid $800 in rent on Friday, they'd put in the rent payment first so if that overdrafted me, I'd get charged $35 for the $2 coffee.

I met with the manager to point this out when asking them to forgive the fees. I was a college student making $9 an hour and their overdrafts had taken basically a week's worth of my income. His reasoning? Well, they were actually trying to help me because larger charges were usually for more important things like rent, so they wanted to make sure those payments went through first. He never explained why that should matter if all the charges were still going through and I was getting penalized, but as a kid with no experience with this kind of thing, I really had no recourse.