It's rather hard to explain, or understand OCD to someone who doesn't have it. There's no rationale behind it, except that there is something chemically wrong in the brain. The OCD person's thought process when they are doing their compulsive behavior is: "I have to do x, y, and z, or something bad will happen." With my brother, it's not as bad as some type of OCD. There's OCD where they feel compelled to check and recheck the locks on the door, or that the oven/ stove/ lights are off, and they will check a lot, around 20 - 50, whatever their "magic number" is. My brother's problem is that he views certain things, people and places as "contaminated." Meaning if he comes into contact with them, or goes someplace contaminated he has to shower or wash his hands afterwards. An example of things "contaminated"? The gunb range, kayaking, fishing, mountain bike riding....these are all things he LIKES. So imagine if you will, someone walking in our house, who he views as "contaminated", our house is not a contamintated place, and probably the least contaminated is his bed in his room. So....imagine someone comes in, and they accidentally sit in his chair, or touches something that he can't "de-contaminate," he flips. Absolutely flips. Part of our problem is that since we can't tell who is "conatminated" or not from his perspective, it makes it rather hard to have guests. There are other factors in my family not having guests, and another major factor is how busy my mother is with her work, she can't deal with guests, but I"YH, next year....Anyways, that is why we don't have guests on Pesach for the Seders at least. I'll hopefully have CJ over for lunch for one of the days though. She's not contaminated, before you ask.