Use sample, that seems cooler.

app/controllers/movies_controller.rb

@@ -1,9 +1,8 @@
 class MoviesController < ApplicationController
     def index
-        @movies = ["Iron Man", "Batman"]
+        @movies = ["Iron Man", "Batman", "Forrest Gump"]
         (0..15).each{ |num|
-            @movies.append(num.odd? ? "Batman" : "Iron Man")
+            @movies.append(@movies.sample())
-            @movies.append("Forrest Gump")
         }
     end
 end