Well...I don't know about that. My sister got marry to this thai's guy. He's 100% (last name: Likitvichit) thai and when he doesn't know people...(even if she or he looks older....but by age he or she might be younger) he tends to call them n'o and not p'e. I think Noi needs to get to the term that she's getting older and accept the fact that she's older. If she has so much respect for others (like some people mentioned here)...than she should use her common sense....you know....people.
well, there are those types of people who are 18 and goes around calling everyone nong. it's something about money, power and respect. people tend to call people their subordinates when they have more money or they at least "think" they are more superior. but seriously, if you do go out and walk the streets in thailand, i gurantee you 100% people will call you p' when you look 18-20 but they are in the 20s. when everything comes, it's always p' first.
Totally Agree with MOILEE!!!!!!!!!!!!!!!!!!!! Noi need to use her common sense.

I live in Thailand for 12 years and i know when people should or shouldn't use P' or nong word.
yea, common sense is not to disrespect.
and yes, like someone mentioned, people tends to refer to the third person again the person they're talking to, so like someone said, she was talking to film, so she was refering to kob as older than film. and i don't think people calls people nong or p' for fashion purposes to tell if they are younger or older, or to make them look younger. but don't get me wrong, there are probably hundreds of people who loves doing it.