My special needs coworker is harassing me what should I do?
Patiently explain to your co-worker that you don't like being harassed. And if it's kept up you will be forced to talk to management. Your co-worker might back off completely. If they don't then just remind them. Also they might back off at first and then start it up again without realizing. Again patiently remind them. But if they have an attitude about it then don't be so patient and lay down the law.
These types of situations need to be carefully handled. First let the manager know that there's an issue. Secondly keep a log. Hand written is better but digital phone notes work too. I worked with a highly functioning coworker who was asking the female coworkers out on a date he crossed the line when he started sextexting. He got suspended for it. Eventually fired for stealing store merchandise. He kept acting broke but we knew he wasn't. A normal individual would of been fired. He also could no longer friendly talk to the female coworkers. Disabled people are not void to the rules but rather fall special to them. It takes more to get them fired but they are not immune to it. Generally what happens is they go over board to the point of not acceptable to the standards of society. Mean while us normal have to suck it up best we can.
Your best choice is to file an ethics report against them for harassment. Sexual harassment is the category it falls under. https://secure.ethicspoint.com/domain/media/en/gui/16000/index.html
I file ethics reports all the time. I use more caution now but this is a situation that calls for it.