Why we say “thank you very much” after good news

Question

I have heard many times in movies when they share good news, like a woman got promoted, she says when telling her friends about the promotion:

I'm now the head of the department, thank you very much.

while of course they had nothing to do with her promotion they were not behind it. Why would she said thank you?

Another situation I also saw in a movie was a girl telling her friend that she got engaged then said about the groom

He is a doctor, thank you very much.

Again, why did she say thank you? I don't understand what it means. please explain for me.

Answer 1

It's common to use "thank you" sarcastically to denote that either (i) someone has given you something you didn't want and you don't really feel thankful, or (ii) that someone has failed to help you and doesn't deserve your thanks. But sarcasm means saying something insincerely, often saying the opposite of what you mean, and that doesn't seem to be the case with your example.

It's also quite common, in all sincerity and politeness, to say thank you in advance or in anticipation of something you have asked for. Sometimes, we may say 'thank you' to make an authoritative request sound more polite. For example, a parent or teacher might tell a child "don't do that, thank you" to sound firmer than "please don't do that", which sounds more like a polite request. Similarly, someone might use the same language to assert their authority in a workplace. For example, a person might remind a subordinate of their title/position in a company by saying "I'm the manager, thank you very much" which essentially means "I thank you not to forget that I'm the manager". Your example sounds like it may be a more playful version of this said between friends as a joke about their new authority.

Answer 2

McGraw-Hill's Dictionary of American Slang and Colloquial Expressions includes this entry:

thank you very much phr.
a (sometimes sarcastic) tag added to a statement for emphasis. (Often used when there is really nothing to thank anyone for.)
I will manage somehow to find my own way out, thank you very much.

In both your examples, the emphasis shows how proud the speakers are.

The same expression can also be used to indicate that someone has said or done something wrong:

(a tourist to a local) I'm Canadian, not American, thank you very much!
(a teacher to a student using a cell phone) You'll stay off your cell phone in class, thank you very much!

NOTE: In pretty much all contexts, the phrase comes off negatively. In your two examples, it sounds like bragging. In my first example, it's a passive-aggressive claim of offence at nothing serious. In my second example, the teacher is being unnecessarily rude.

If someone is simply correcting someone else, they might use "Actually, I'm Canadian" or "Close, I'm Canadian". If someone is actually offended by the mistake (as opposed to claiming offence in order to put someone else down), they would show it in a different way.