The only thing off limits around here is sexual activity involving minors, although 16-18 years old is a gray area.  Beyond that, I would be surprised if anything would be beyond the pale of this forum.  Necrophilia, bestiality, violent rape, and more may have limited, if any audiences here.  Or they might.  But it's pretty rare (if ever) to see negative commentary on this forum if a story reaches a forum member's "ick" threshold.