Do you have it or know someone who has it?
Symptoms
Common obsessive thoughts in OCD include:
-Fear of being contaminated by germs or dirt or contaminating others.
-Fear of causing harm to 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.
-OCD signs and symptoms: Compulsive behaviors
Common compulsive behaviors in obsessive-compulsive disorder (OCD) include:
-Excessive double-checking of things, such as locks, appliances, and switches.
-Repeatedly checking in on loved ones to make sure they’re safe.
-Counting, tapping, repeating certain words, or doing other senseless things to reduce anxiety.
-Spending a lot of time washing or cleaning.
-Ordering or arranging things “just so.”
-Praying excessively or engaging in rituals triggered by religious fear.
-Accumulating “junk” such as old newspapers or empty food containers.
I realized this when I was in High School... Like when I forget the pen that I'm accustomed to writing with... I really can't use any other color pen, it messes up my notes. 
That's just an example lol. 
