How can you disable a RigidBody?

I have a gun that can be picked up. Because it has a RigidBody it falls as soon as you equip it. How can you disable it or prevent it from falling. I tried

var Gun : RigidBody

function PickUp ()
{ = false;

This should do it!

var Gun : GameObject;

function PickUp()
  Gun.rigidbody.isKinematic = false;