Many years ago when I was in College, I would fly home every fortnight to see the family (I was 17)
The plane was a 40 seater Saab from memory and used to do a regional run. One FA, flight left from the tarmac etc

Anyhow, I was never questioned or looked at any differently each time I flew, though i was always the youngest on the plane by at least 20 years and the rest of the PAX seemed to be government or corporates flying to the same destination as me.
One particular day as i was going up the stairs of the plane, the FA looked me up and down like I had the plague and shouted something to the effect...Why was I on the flight, I didn't look old enough to travel, where were my parents etc etc (you can fly here in Oz without an adult at around 15 i think)
It gave me the greatest of pleasure to tell her that yes I was old enough and in fact that day was my 18th birthday (which it was) She didn't utter another word, however the Deputy PM of the country was seated next to me and brought me some lemonade to celebrate !

Probably the only time an FA made me feel very uncomfortable regarding her attitude