I've had a life so far, that has exposed me to all sorts of really gross stuff - partially because such things interest me, and partially because it's been part of some jobs I've held - dealing with everything that comes out of all kinds of animals ! I generally have a very strong tolerance for things that other people may not be able to handle.
So I amuse myself when I find I'm grossed out by odd and unexpected things, such as :

Touching mixed organic greens that have badly wilted and now are somewhat slimy ... ick !

Preparing pet food, and getting the juices on my hands - yuk !
(maybe because I haven't eaten creatures in many years ...)

Seeing anyone spit on the sidewalk - nasty !

Watching some people eat ... barf !

What sorts of things get to you ? Rational, or not ?