Definitely not appropriate. Family relationships are based on love, respect, and appropriate boundaries. This kind of description involves extremely abnormal and unethical behavior. It is not something that should be part of any story or real - life situation. We should uphold positive family values and ethical standards.
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.
Definitely not. In most cultures, there are ethical and moral boundaries. Aunty erotic stories cross those lines as they often objectify and sexualize family - like relationships in an improper way. We should promote literature that respects family values and human dignity.
First, if it's just a stupid joke among peers, you can have a conversation with those involved about appropriate language and respect. Tell them it's not okay to use such vulgar terms in relation to your son.
It's not appropriate at all. In a healthy family environment, the relationship between mom and son is based on love, respect, and appropriate family values. Erotic stories are adult - oriented and violate the normal family ethical relationship.
Well, if not in a vulgar sense, 'huge cock' could potentially be a misnomer or a very strange way of referring to something large. Maybe it's a big rooster on the family farm that the stepmom has some sort of story related to. But this is a very odd and uncommonly used way to phrase it if not being inappropriate.