How the conversation went in my head:
Me: I'd like to pay off my credit card- a hundred from my checking account.
Teller: A hundred?
Me: That's correct.
How the conversation apparently went in her head:
Me: I'd like to pay off my credit card- eight hundred from my checking account.
Teller: Eight hundred?
Me: That's correct
And now I'm out $700 in cash because I used a long "ay" sound instead of an "uh."
(Also, I'm don't normally have even enough to pay off $100 on my credit card, but I got my school loan refund check. And I suppose it's for the best that I don't just have that cash sitting there in my account.)