Does "mi niño"have any romantic connotations?
If someone were to say "mi niño" to a guy her age, could it be seen as flirting?
2 Answers
Yep exactly. It's seen as flirting
Not necessarily. Flirting is in the attitude, tone, body language.
The original Macs has a hidden feature whereby you could get them to say, in a robotic voice: "Oh baby insert your disk and play with my mousie". It was funny, but certainly not flirting.
With the right twist, however, you can fix someone with a scorching look and whisper, for example: "mmm, my salty peanut!", and get some serious flirting going.
So, mi niño just means "my child". There are plenty of different contexts to provide different interpretations.