Why I Let Students Call Me Sir Even Though I'm a Woman

From eves-rib.blogspot.com

Let's start this by getting something straight: I am a woman, always have been a woman, and always will be a woman. I haven't had a sex change and have no desire to be a man.
Now, moving on. . .
At one of my first teaching jobs almost all my students called me, "Miss". Except it was a Spanish speaking country, so sounded more like, "Mees". At first I didn't like it.
The word "Miss" takes me back to an era when men wore top hats and women wore petticoats. "Miss" and "Master" simply aren't used that much. Besides, the word, "Miss" should be for young (under 18) women or unmarried women. While I was single, I was over 18. And besides that, all female teachers were called that, no matter their age, civil status, or where they taught (school, university, etc).
But, if you can't beat them then join them, so I did. I figured it was a way for my students to show respect, so "Miss" I became.
Fast forward a couple years . . .
I don't tell my students what to call me, but they pretty much call me one of four titles:

• Teacher
• Professor
• Sir
• My first name

I moved back to Asia and was teaching at a university when one of my students called me, "Sir". The student who called me sir spoke English very well and had good etiquette. I hesitated and was about to say that men are called sir and women are called ma'am, when I thought better of it and decided I'd rather be a sir than a ma'am. Ma'am reminds me of old ladies who you have to help across the street.
In addition . . .

1. I teach at a university I'm not really a teacher (grades K-12)
2. I wouldn't be considered a professor back home (no PhD)
3. Some students aren't comfortable using my first name due to respect and hierarchy
4. My last name is long and hard to pronounce

So in this case, if a student wants to call me, "Sir" I'll let it slide.