I don't know what this is!
I have looked at this comment of theirs and concluded that they possibly saw the growth/inflation/expansion and transformation fetishes in the game and thought it was related to a fetish where a character either becomes rubber-like or transforms into an inflatable object (usually a pool toy) and in the end for both options the characters breasts, butt, belly, and/or other body part becomes larger. This can also be applied to the gender swapping fetish.