Going without shampoo?

Although I have never gone without shampooing my hair, I do have a co-worker that has not washed his hair with shampoo for over 2 years. His hair is oily looking, but it does not smell. He brushes it many times throughout the day, and keeps it in a ponytail. ( He is growing out his hair for Locks of Love) So... you can bet that it will look greasy... it is supposed to.