I have a weird rule imposed on myself. I won't get anything that a friend has, design and/or placement wise. Unless it's a common theme. Or if I have work in progress already started on.
For example, if I were to ever get my hands tattooed, and I see that my friend just got a pair of hannyas on his hands, then I couldn't get hannyas on my hands. So it's kind of a race for me to get the tattoo designs I want before all my friends get them.
Also, I used to want a praying hands tattoo, but Drake ruined that for me.