Sharing such stories is completely inappropriate and violates moral and ethical boundaries. This involves vulgar and inappropriate content that should not be spread or discussed in public or private in a positive way.
Using that expression is not proper. Here is a story of a loving mother. A mother always cooked her child's favorite meals. When the child had to move away for college, she sent care packages full of home - cooked goodies regularly. She would also write long letters with words of encouragement and love, which made the child feel that her love was always there no matter how far away.
In a civilized society, we uphold values such as respect, family harmony and propriety. 'Cum in step mom stories' clearly violate these values and thus have no place in literature.
Educate yourself about appropriate family values and boundaries. By understanding what is respectful and moral, you can easily recognize and avoid such inappropriate stories. Also, encourage those around you to uphold positive values.
Assuming 'pussy' is a cat here. My first story about a cat named Pussy started on a rainy day. I saw this small cat trying to find shelter near my porch. I opened the door and let it in. It was a bit scared but soon got used to the new environment. I gave it a warm towel to dry off and some milk. That's how our friendship began.