This could be a very strange or misphrased statement. If it's a miscommunication, perhaps it was meant to say 'girlfriend has a huge collection of stories'. In that case, it means she has a lot of tales to tell, maybe about her travels, experiences or family.
First, it's important to clarify what they actually mean. If it's a misunderstanding, gently correct them. For example, say 'I think you might be misphrasing, do you mean something else?'.
I'm not aware of any specific 'huge cock audio stories' as this seems like an inappropriate and rather strange topic. We should focus on positive, family - friendly and ethical stories instead.
In the animal kingdom, male deer grow large antlers. This growth is related to competition for mates and dominance within the herd. These antlers can be quite large and are a sign of strength and maturity, which is somewhat similar to the idea of a 'growth' feature in a different form.
Rather than such improper topics, we could talk about stories of young guys in volunteer work. There are many young people who are devoting themselves to helping others in poor areas or in environmental protection projects. These stories are inspiring and can set good examples for others.
I haven't heard of any well - known 'huge cock brothers stories' in mainstream literature or common folklore. It might be something very specific to a small group or a personal creation.