For example, the coffee shop this morning had a computer glitch. I wanted a coffee, and had exact change, but the girl kept saying "I cannot help you, our computers are down" I just want a coffee... here is the money, give me a coffee. The Manager finally came over and gave me a coffee, no charge. 
But had he not been there, I would never have got it. All because the computer was down.
I once bought something at a store for about $9 and gave the cashier a $10 bill. She accidentally entered $100 as the amount tendered, and she started to count out $91 in change for me, until I stopped her and explained that she only owed me a dollar.
P.S. She thanked me profusely.
I believe it.
One of my Japanese friends stuffed a spread sheet and when I fixed it for her she said, "How can I thank you?" So I wrote something on a slip of paper and said, "Translate that into Japanese." She was puzzled but did it so now I know that mijikai ita ni mai is Japanese for two short planks.
Your shop assistant was definitely a bit mijikai.
@Didge:
LOL! So in English you were implying she was thick as two short planks, but in Japanese you were saying don't worry about it (at least that's how Google Translate interprets the phrase). Did you figure that out yourself, or did you learn it from your former Japanese boss?
No, that would be a happy coincidence. That's the translation she gave me. Perhaps she was having a joke at my expense.
@ Didge:
But did she know the idiomatic English meaning?
Quien sabe? (That's Japanese for "Your guess is as good as mine."
Dommage. (That's Japanese for "tough toenails.")
@T(h)ink
Lol, I found another translation:
Don’t worry about it = ki ni shinai de kudasai.
(toenail or fingernail = tsume)
@Didge
Lol - I don't think that the true meaning of this sentence would work in Japanese; I found:
(extremely silly = hijō ni orokana) or (in a kinder way: you are so funny = (omoshiroi hito desu ne).
@ Marianne:
I looked up "mijikai ita ni mai", word by literal word, and it seems to say "short board two sheet", but idiomatically, the whole phrase seems to mean "don't worry about it." Maybe it metaphorically means two short planks on a foot bridge are easy to traverse, or something like that?
Lol - I found these definitions:
mijikai = short
ita = plank or plywood
ni = two
mai = sheet, plate, board, ... (that should, actually, stand for thick)
The original meaning of "thick as two short planks" is, as already said above, a very different one:
http://www.phrases.org.uk/meanings/as-thick-as-two-short-planks.html
Oh - there might be even three planks - lol.
@T(h)ink
Dōmo arigatō (どうもありがとう)
(Quel dommage que les sentiments ne soient pas des preuves! - Madame Roland)
@ Marianne:
"Dubito, ergo cogito, ergo sum."
@T(h)ink
"Quid enim sum? Res cogitans!"
Agnus Dei, Google
Lol, my great-grandfather said something like that in his diary (in translation): "But what am I? A dream. I have dreamed myself."
And the Sibyl said to Claudius when he asked (while awaiting the ferryman), "What's next?", she answered, "You'll dream a different dream, I promise you."
Lol, are you referring to the "I, Claudius" novel?
No, I did not see the BBC TV series.
@ Marianne:
Yes, the TV series, "I, Claudius" with Derek Jacoby. Really excellent.
@T(h)ink
Well, I didn't see the series, as I only read about the story, but it must be good!
Yes, all the episodes used to be on YouTube, but now most of them have been blocked for copyright reasons. Here is one that I found still available.(and I hope also in Switzerland)
It looks interesting, and I saved the link to watch it later.
Thank you, T(h)ink.
You're welcome, Marianne.
Nihil erat. (how did they say 'you're welcome' in Latin?) 
Opinions differ very much about an answer to "thank you" in Latin, and I would also opt for the more simple "nihil erat".
The answer I prefer is "Nihil est de re dicendum" (no need to speak about that) - but that is my "gut feeling" - and it sounds the nicest - lol, as I am really no expert and I don't like the other proposal "salutatio" (bold for the accents). Funny, I could not find a mention "servus tuus" or "serva tua" (with or without "sum") as an answer to a "gratias tibi", for instance.
Lol, I'm surprised it isn't used in Latin literature somewhere. Maybe the ancient Romans weren't used to being thanked, at least not in the areas they conquered.
That is quite possible. I was also trying to find answers, but there were too many assumptions, errors or lacking explanations.
Yes
Not so much of us in the older generation but the younger ones don't know any other way. They can't even make change in their head anymore. I've heard that at more businesses over the last few years : Sorry, but the Computers are all down. Geez, what happened to pocket calculators ?
Oh yes, computers are extremely useful, but when they or their programmes fail, most equipments cannot be run manually, and the operators can only call the computer specialist in charge - lol.
There is also a problem with modern engines and mechanisms, like with cars; you can't repair anymore with "bits and pieces" in emergency situations.