- This happens to be my house!
- That happens to be my mother you're talking about!
- I happen to live here too!! don't leave your garbage everywhere!
■ Somebody/something happens to be something: used when telling someone something in an angry way.
■ happen to be/do something used to tell somebody something, especially when you are disagreeing with them or annoyed by what they have said.
■ happen to do sth: (3) SPOKEN. used for expressing an opinion firmly, because you are angry.
.... LDOCE, OALD, Macmillan