Most people with OCD fall into the following categories:

• Washers are afraid of contamination. They usually have cleaning or hand-washing compulsions.
• Checkers repeatedly check things (oven turned off, door locked, etc.) that they associate with harm or danger.
• Doubters and sinners are afraid that if everything isn’t perfect or done just right something terrible will happen, or they will be punished.
• Counters and arrangers are obsessed with order and symmetry. They may have superstitions about certain numbers, colors, or arrangements.
• Hoarders fear that something bad will happen if they throw anything away. They compulsively hoard things that they don’t need or even use.

The character Sheldon Cooper in Big Bang Theory is typical, if wonderfully comically portayed, of such compulsions - watching him clearly illustrates the irrational nature of such actions. Watch him and see if he doesn't irritate you as he does his friends.

Common obsessive thoughts in OCD include:

• Fear of being contaminated by germs or dirt or contaminating others
• Fear of losing control and harming yourself or others
• Intrusive sexually explicit or violent thoughts and images
• Excessive focus on religious or moral ideas
• Fear of losing or not having things you might need
• Order and symmetry: the idea that everything must line up “just right”
• Superstitions; excessive attention to something considered lucky or unlucky