Definitely not. Sharing something like that with a sister is highly unethical. Family relationships are based on respect, love, and appropriate boundaries. This kind of sharing violates those boundaries and can cause discomfort, harm to the relationship, and is not acceptable in a civilized family environment.
I'm still not clear on what a'mom suck friend story' is supposed to be. But if we assume it's about a positive relationship between a mother and a friend, it could be a story where a mother befriends her child's friend's mother and they support each other, like sharing parenting tips and having playdates for the kids together.
This is extremely inappropriate behavior. Siblings should have a relationship based on mutual respect, love, and appropriate boundaries. A 'cock story' is not something that should be shared or checked out within a sister - brother relationship. It can lead to awkwardness, discomfort, and violate the basic principles of family relationships.
Such a story is not something that should be discussed as it is likely to be immoral and against social norms. It's important to focus on positive and appropriate content.