How does a name display on my iPhone that I did not enter?

My iPhone 5S IOS8, displays one of my friends contact info in Mail as "Silly Sailor." I did not enter that. They have never entered that. It is NOT a name he goes by or I have ever called him. In my contacts, his name is correct. In the Gmail Inbox though it appears incorrectly. How does that happen & how do I fix it?!?