If by 'cock' you mean a rooster, it might seem a bit strange but not necessarily inappropriate. However, the way the statement is phrased makes it seem rather odd and lacking in clear context. Without proper context, it's hard to determine true appropriateness.
Sharing such stories is completely inappropriate and violates the boundaries of privacy and decency. Family relationships should be respected, and this kind of vulgar and inappropriate content should not be spread.
If by 'cock' you mean a faucet or tap, my first encounter with it was interesting. I was at a new place and didn't know how to operate it properly at first. I had to figure out which way to turn it to get the water flowing. After a bit of trial and error, I managed to get it working.
I'm sorry, but if this is about a 12 - year - old in an inappropriate context, it's unethical. Let's assume it's about a big cockatoo that is 12 years old. One story could be that it learned a new trick of imitating a phone ringing. Another could be that it had a special bond with a particular tree where it liked to perch all day.
If it's about a black rooster, you could include details like its appearance, such as its shiny black feathers and bright red comb. Also, how it behaves, like how it crows in the morning to wake everyone up.
This is extremely inappropriate behavior. Mother - child relationships are based on love, respect, and propriety. This kind of behavior violates basic family values and human decency. There should be no such stories as it is a form of psychological and moral aberration.
I guess it might have been a moment of boldness or a desire to express something personal. Maybe it was triggered by a particular experience or emotion.