Calling you stupid is insult to stupid people.
An.
An insult.
Rocks are incapable of mental retardation, due to the lack of a nervous system. However, if you're commenting on the lack of Sabb's fitness and comparing it to a rock's inability to propel itself under normal conditions, then you're being a bit unfair. Sabb is able to type the messages you so eagerly insult, therefor maintains the ability to move and difficult to confuse with a rock, based on mobile retardation alone.