For the record, shit porn is usually referred to as 'scat'. It's some pretty nasty stuff. Pissing is usually referred to as 'watersports' (I actually had a girl that liked to pee on me). You also have some guys into puking (girls either puking on them, forcing themselves to vomit while having sex, and/or deep throating till they vomit)... Nasty stuff as well. Forget the name of the 'popular' Internet chick who does that stuff... Something 'Holly'. I seen some of it... Again, nasty.
You also got 'snuff' films where girls are killed (mostly fake though... Mostly)... You have adult baby fetishes where grown men/women dress up as babies and wear diapers. You got medical fetishes which includes (but not limited to) enemas, doctor/nurses, gyno exams (sometimes under the 'guise' of being voyer) and some real weird shit like people in full body casts... ect.
There is bestiality... Pretty much sex with animals... I once saw this .avi movie where this chick sucked a horse off till he came so hard down her throat she puked two loads of horse cum.
Nudist porn... Bascially an 'excuse' for people to see little boys/girls naked (most of the time).
Moving on to some lighter stuff you got guys into BBW or chubby girls... Got guys who like hairy women... Guys who like mature women... Interracial fucking (straight and lesbian).
Man, there is all different kinds of weird shit out there. I've seen most of it. Scat, snuff films, and puking take the cake for the most insane shit I've seen though.