I got a few.
Big Country - One of my Best friends called me that once and it has stuck.
Batman - Last name starts with Bat
God Father - I was a priest one year at Halloween party at the local pub I go to. Now all the girls there call me that.
Easy E - There are about 5 guys at the local pub and we all have similar names. I am Easy E, there is Sleaze D, Triple T, Ki Ki, Sweet P.