Is there a way to mock methods that has return type 'Object?

public class classSomething 
{
   public object MethodSomething()
   {
      throw new NotImplementedException();
   }        
}

[TestFixture]
public class TestClass
{
   [Test]
   public void Test()
   {            
      using (RecordExpectations recorder = RecorderManager.StartRecording())
      {
         classSomething mock = new classSomething();
         mock.MethodSomething();
         recorder.Return(new object());
      }

      classSomething c = new classSomething();      
      //Assert code ..
   }
}

recorder.Return(new object());