lol @ people making the distinction between "a" and "er" it's the same thing
I don't care if my friends use it (or anyone but if you say it I'll give you a side eye because it's just very awkward). Even my friends don't use it (but like I said I wouldn't have a problem with it).
The only time I would is if someone is using it with malicious intent. Never happened to me in my life but it could, that's when it's like
Singing/rapping I don't give a **** because it's in the song you're singing