What does the launch lug in a model rocket?

Model rockets launch by sliding up a rod/wire that is pointing toward the sky. A launch lug is a small tube (like a drinking straw on a small rocket) glued to the side of the rocket body. You slide the small tube (launch lug) down on the rod. The launch lug and rod guide the rocket to start it in the correct direction until it gets going fast enough that the fins can stabilize it.

Visit the links below. The first picture shows a rocket on the rod. It's a little hard to see but the rod goes through the launch lug. At the very beginning of the second link, they are sliding a large rocket lugs onto the rod.