The phrase 'black cum erupt mouth story' is really hard to decipher without any background. It might be a creative or experimental phrase from some niche genre of writing or art that I'm not familiar with. Maybe 'black' could refer to something negative or mysterious, but it's all speculation without further details.
The term 'cum inflation' is rather strange and not a typical concept in mainstream stories. In the context of a 'gay story', it could be that the story is exploring unique relationships or experiences within the gay community, and this 'inflation' might be a metaphorical or symbolic element, but again, this is all just conjecture without more information.
I'm not entirely sure specifically as it could vary greatly. It might be about self - control in a sexual context within the gay community, but this is a rather private and often not publicly discussed in detail topic.
There is no evidence to suggest that it is a popular type of story. Popular gay - themed stories usually deal with more common themes such as coming out, love, discrimination, and acceptance. The 'cum inflation' part makes it seem very unusual and not something that would appeal to a broad audience. So it is highly unlikely to be a popular story type.