Perhaps 'Dad, I'm not Mom. Please refrain from what you're doing.' This version is more polite and still gets the point across that the father's actions are not acceptable in the eyes of the child, whatever those actions might be.
We could rewrite it as 'Dad, I'm not Mom. Stop that inappropriate behavior.' This makes it more general and appropriate.
One way to rewrite it could be 'Dad, I'm not Mom. Don't do that.' This is a simple and straightforward way to convey that there is some behavior that the child is objecting to without using unclear or inappropriate language.
It could be a completely jumbled and unclear statement. Maybe it was a miscommunication where words were mixed up. For example, it could be that someone was trying to say something else and it came out all wrong.
If we assume 'cock' is referring to a rooster, it could be 'Mom measures my young rooster.'
Another option is 'In a CBT story, no excessive dominance is allowed'. This rewrite keeps the focus on the CBT aspect and clearly states that there should be no extreme form of dominance in the story, which was what the original phrase was trying to imply in a rather unclear and inappropriate way.
We could rewrite it as 'The Story of a Rock - Hard Object and Its Transformation'. This way, we remove any potential inappropriate connotations and make it more straightforward and easy to understand.
One way could be 'Beta submits a story about a gay relationship.' This gets rid of the inappropriate terms and makes it more understandable.
We could rewrite it as 'Dad catches a boy (while he is) making up stories about his son'. This makes it more of a situation where the father discovers a boy creating untrue tales regarding his son.
Perhaps it was meant to be 'The girl had a couple of stories' which is a much more common and understandable phrase.
Perhaps 'Shape - change item stories' would also work. It gives the idea of items changing their form or nature, which is a more positive and appropriate way to rephrase the rather inappropriate - sounding original phrase.
One way could be 'My wife has a strong attraction or passion for something (describe the appropriate thing).' For example, 'My wife has a strong passion for reading stories.'
You have such a lovely item for me.