Explicit private Interface implementation

Program.cs

class Program
{
    static void Main(string[] args)
    {
        var x = new Test();
        var y = x as ITest;
        y.Foo();
        // "x" hasn't a Foo() method but "y" does.
    }

    class Test : ITest
    {
        void ITest.Foo() 
        { 
            Console.WriteLine("Foo!!!");
        }
    }

    interface ITest
    {
        void Foo();
    }
}