There is no evidence to suggest that such activities occur in a gym environment. Gyms have rules and ethics in place to maintain a proper and respectful atmosphere for all members. This kind of description violates the basic norms of a public fitness place.
The term 'big cock wife' in a sexual context is not suitable for public discussion. However, if you mean it in a non - sexual, perhaps a misnomer or a made - up phrase in a non - vulgar sense, there are no such pre - made stories. We should stay away from vulgar and inappropriate expressions.
I'm not sure there are specific so - called 'big cock wife stories' in a proper sense. It could be some made - up or inappropriate tales that we should avoid promoting.