This could fit equally well with brain hurting, professional darwinism, or never shopping (banking) somewhere again, so I just picked one :-)
Some of my friends started a new scout troop this year for their girls. Babybartfast won't be old enough to join until next year, so I'm on the rosters as one of the adult helpers for the troop but I don't really participate in much yet. When my friend Alice went to open a bank account for the troop, she was told by the council that she had to go through LocalBank because all the troops had accounts there and they knew what to do. She opened the account, got the little book of starter checks and deposit slips, ordered some real checks, etc. Alice had several small deposits totaling a few hundred dollars (everyone's sign-up fees), then one larger deposit and a larger withdrawal at the same time - the deposit and withdrawal were about the same amount, but she had to put the money in and out for accounting purposes. That was back in October - since then, it's mostly been a stream of small checks for various supplies the troop needs.
When the real checks came, Alice realized the bank account number was different than on her paperwork. LocalBank wouldn't tell her who the account belonged to, but they were okay with her having a package of checks to draw on that account? They finally were willing to tell her that the other account belonged to a different scout troop, and with some begging she got them to tell her the troop number, and with that she was able to track down (via the council) who the troop leader was.
As it comes out, the starter checkbook (checks and deposit slips) they gave Alice was for the wrong troop. All the small deposits went into our troop account, because Alice was doing those with the deposit slips at the bank, but the checks were coming out of another troop's money! And they hadn't noticed for three months! The larger withdrawal would have bounced if Alice hadn't happened to have used one of the starter deposit slips for the larger deposit at the same time.
With the help of the council, they finally got everything resolved just in time before cookie sale season. The real brain-hurty part: the other troop leader (and person responsible for the other troop's checkbook) is an accountant

At the next meeting the council held for troop leaders (which they do once a month), the council staff stressed VERY strongly that everyone needed to actually check their troop's bank balance on a regular basis . . .