That reminds me of when I used to work in a tooling warehouse. Customers would come in with a bolt and ask for 10 more of the same. Well it looks like 3/8" but what the hell thread is that? Commence my running around comparing it to every bolt of that size in the building.
Metric was much easier. Except for that time when I was asked for a M10 tap and supplied a M10x1.25, only to have the customer come back later and ask me why his bolts didn't fit the holes he'd tapped!
