A shortened version of the word madam, which was formally used when addressing women in the days when etiqute and common curtesy were commonplace.
The term Ma'am is often coupled with the word No, to create the phrase "No Ma'am", which flows off the tounge very well if you have a Southern US accent.
Ma'am: Excuse me officer, could you tell me the route to Texas, I seem to be lost?
Officer: Sorry Ma'am, that is something I am unable to do at this time.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.