Disturbing thoughts

ok so, i have a lot of strange thoughts that many people i know find weird.
Usually the things are sick.
An example is this:

At my college there used to be a woman that worked in the canteen called "Mum" and she was about 80. (i had no attraction to her whatsoever)
however when i saw her i used to say things like "phwoarrr" and "i'd love to stick fly eggs up her bum because its a nice warm environment and nice and moist, and when they hatch i will be waiting for the maggots to drop into my mouth", "i love the fact the mom gets stiffer and older everyday, and i cant wait for the day she relies on me to take her to the toilet"

Me saying these sorts of things really do not bother me, but they seem to sicken others.
IIN?