Hi,
Often we come acroos the expression, "save my ass." What exactly does it mean? It means to save you. In mild humour, it suggests that your ass is the most important part of you, so it 'represents' you.
Is it normally socially acceptable and politically correct especially in public? It depends on the situation you are in. Generally speaking, I'd suggest you should avoid references to your 'ass'. Don't say it to the Queen, don't say it in a job interview, don't say it to me. But if you want to say it to your friends and you think they will find it slightly amusing, then go ahead.
I have assumed in this post that you know where and what your 'ass' is. If you don't, let me know.![Smile [:)]](/emoticons/emotion-1.gif)
Best wishes, Clive