Introduction
I thought that the tip was really more interesting, but please do not use such title and then depress myself with that.
An elegant solution is:
List<int> myList = new List<int>() {1,2,1};
Console.WriteLine("All numbers are{0} the same",
myList.Any((i) => i != myList[0])? " not":String.Empty);
Console.ReadKey();
Just a line, not any loops, and multiple unnecessary stuff.