What's [happen to] in this?

Question

I've always thought that [happen to] is the phrasal verb indicating chance, which can be replaced as [by chance] such as...

1. I happen to have some money in my pocket.

   = I have some money in my pocket by chance.

2. Do you happen to be a teacher?

   = Are you a teacher by any chance?

But, sometimes I stumble across what I can't use the above rule. For example...

A,B,C are at the table where B prepared a meal for C.

A: (Went ahead and tasted some) It's so good!

B: Hey! Don't just eat it without asking! This happens to be for C.

Here, the meal can't be something prepared by chance, more like it's fixed by B on purpose. Then what's the exact meaning of [happen to] in this sentence? And what would you recommend as the alternative words rather than [by chance]?

Answer 1

Happen to do something has a few meanings. You know to do something by chance:

I happen to have some money in my pocket. (I even didn't plan it)

I happened to meet an old friend in town. (I met him by chance)

In spoken English, the phrase can be used for asking something politely:

Do you happen to be a teacher?

Do you happen to have an extra pencil?

It can also be used for expressing an opinion firmly, because you are angry, and this is the meaning you are asking about (it's common in spoken English too):

Hey! Don't just eat it without asking! This happens to be for C.(the speaker is obviously annoyed)

I happen to live here too – don’t leave your rubbish everywhere!

Source: Macmillan Dictionary