Stupid things that instantly piss you off

[MM_QFC!]

People who don't say "You're Welcome" when I say "Thank You." Instead they say, "No problem," or "Thank you."

"Thank you" to "Thank you??"

It doesn't piss me off, but it does make me grimace.

+1
I think that "no problem" is almost a negative choice in response, especially by itself (instead of, "oh it was no problem at all; I was glad to help by..."); maybe it's a not so good habit that people get into, by using it as a quick response?

The other very appropriate time to say thank you - IMHO - is in the retail setting, at the counter when a customer has purchased something and it's the clerk who should be thanking the customer for their business but, instead I've been handed my change oftentimes without any acknowledgement nor appreciation for my business - hmmmph!
When standing in line, I've actually heard other customers thank the clerk when they are given their change, which is still their money, after all