i dunno but similar to what redeva has said, i actually do think that excessive stretching of the anus will lead to it being less stretchable? as in, the muscles wont be able to function as well as before, so the back passage becomes 'loose'

although maybe it wont be as extreme as being unable to control your bowels...just that it just doesnt become as 'tight' as it used to be?

as for 'natural' stuff that's rather 'large' in size i dunno. but i think there's a difference between stuff the body produces, and stuff that is external? like i mean the body wouldnt make the 'natural' stuff into a size that it wont be able to expel....

but that's just my warped way of thinking. i better leave it to the professionals to clarify this