using static System.Console;

using System.Collections.Generic;

using System.Linq;

​

public static class Sorteio {

    public static void Main() {

        var lista = new List<string>() { "Alaor", "Joseval", "Salustiano", "Gomide", "Castro" };

        foreach (string value in lista.Shuffle()) {

            WriteLine(value);

        }

        WriteLine("////////");

        foreach (string value in lista.Shuffle().Take(3)) {

            WriteLine(value);

        }

    }

}

​

namespace System.Collections.Generic {

    public static class IEnumerableExt {

        static Random r = new Random(DateTime.Now.Millisecond);

        public static IEnumerable<T> Shuffle<T>(this IEnumerable<T> list) {

            T[] array = list.ToArray();

            for (int i = array.Length - 1; i > 0; i--) {

                int j = r.Next(i + 1);

                T tmp = array[j];

                array[j] = array[i];

                array[i] = tmp;

            }

            foreach(var item in array) {

                yield return item;

            }

        }

    }

}