I guess in a way he does use two words together but in his world I think he uses them as one. Luke has two sayings that Mom and I just adore. They are "oh man" and "oh no". "Oh man" is definitely is our favorite. Whenever he says that phrase he does it with a southern accent and cracks Mom and I up.
Luke can also ask for things he doesn't see. This almost exclusively applied to food. When he gets up in the morning or after his nap he will walk over to the refrigerator, grasp the handle, and say milk or juice over and over again. If we don't get him any right away he kicks vocabulary to the curb and goes back to screaming.
When it comes to screaming Luke was much worse than his sister. A lot of times he squeals or screams to hear his own voice or because he is excited. Other times he does it to show his displeasure or for attention. We don't cave into his demands and try to redirect him when possible, but so many decibels close to your ears can make you lose patience quickly. Luckily his screaming is on the decline as he is better able to handle his emotions and use words to describe how he feels.
In closing here's a list of Luke's words. I don't think it is complete but it does show the breadth of his vocabulary. Also, he isn't speaking the King's English when saying these words. Most of them only Mom, Alyce, and I can understand.