How common is it for natives to use ain´t in conversations? Would it sound natural if a foreigner used it?
***** NOT A TEACHER *****
(1) What an interesting question.
(2) When you say "natives," you have to understand that in the United
States -- as in all other countries -- people belong to different economic
and social classes.
(a) I think that in certain groups, "ain't" is used frequently -- even
(i) I'm a senior citizen (old person), so I do not listen to or like most of
today's music, but I think that "ain't" is used in some of today's music
for young people, ain't it?
(b) I really think that if anyone regularly used "ain't" in his/her speech,
s/he would never get elected to a high governmental position. Surely, the
American people would be embarrassed if their president were an "ain't"
(3) I'll end my post with a personal observation:
I spent many years among teenagers and adults who were learning English,
and I was astounded that I never heard any of them use that word.
Not once in many years did I ever hear it. I thought they would pick it up
from popular culture. I was dead wrong.
(4) Most Americans ain't going to use "ain't" because it is considered
a sign of an uneducated person.
(a) "Educated" people might occasionally use it for fun and emphasis:
Martha: Did you see Mona yesterday? She is getting so old!!!
Joe: Ain't that the truth!!!
(5) I suggest that you never use it. If you do, people ain't gonna
respect you or give you a good job.
***** Thank you for your question *****
P. S. That's why we say: I am your best friend, aren't I?
Nobody wants to say: I am your best friend, ain't I?