The word "sicko" is slang and is often used to describe someone who has strange or disturbing thoughts or behavior. It suggests that the person is mentally unwell or perverted. Full definition
Don't get me wrong, I'm not some sort of sicko who gets his jollies off on death and destruction. (truckingtruth.com)
I suspect the Christian hell holds a place for sickos who would wish for such twisted things. (religion.blogs.cnn.com)
I would prefer to just skid across all the online formalities and take you to see a movie, but you are aware that the net is filled with sickos and weirdos. (fsat.ru)