Randomly switch between animations (2D)

I have 2 idle animations. One where the player's hair sways while another has the player swaying his arms a little. However the arm-swinging animation occurs in a loop, after the hair animation to the point where it appears unnatural. However I couldn't find a way to make Unity randomly play the swinging arm animation when idle. So far my code is...`

 public float maxSpeed = 10f; //maxWalk speed
 bool faceLeft = true; //check to flip animations
 public float Speed= 0.0f;
 public float move = 0.0f;
 public float RandomMove = 0.0f;
 Animator anim;
 // Use this for initialization
 void Start () {
     anim = GetComponent<Animator> ();
 
 }
 
 // FixedUpdate is called at constant rate
 void FixedUpdate () {
     float move = Input.GetAxis ("Horizontal");

     float RandomMove = Random.Range (0,5);
     anim.SetFloat ("Speed", Mathf.Abs (move));
     anim.SetFloat ("RandomMove", RandomMove);

     GetComponent<Rigidbody2D>().velocity = new Vector2(move*maxSpeed, GetComponent<Rigidbody2D>().velocity.y);

     if (move < 0 && !faceLeft)
         Flip ();
     else if (move > 0 && faceLeft)
         Flip ();

         
 
 }

 void Flip () {
     faceLeft = !faceLeft;
     Vector3 Scale = transform.localScale;
     Scale.x *= -1;
     transform.localScale = Scale;


 }

But the random number generator doesn't change the parameters in the animator...