how do i make my character do some moves if i dont move him for a while

Questions & Answers
1

how do i make my character do some certain moves if i dont move him,.,.,like look around,yawn,cough

2

This is done usually at the animation level: when the character gets still for some time, play the idle animation in loop mode. The best way to detect idle state is to keep track of the character velocity: this allows you do differentiate idle, walk and run states - something like this (script attached to the player):

private var lastPos: Vector3;

function Start(){
  lastPos = transform.position;
}

function Update(){
  // calculate player velocity:
  var vel = (transform.position - lastPos).magnitude / Time.deltaTime;
  lastPos = transform.position; // update last position
  if (vel < 0.2){ // play idle when stopped...
    animation.CrossFade("idle");
  } else if (vel < 2.5){ // play walk at medium speeds...
    animation.CrossFade("walk");
  } else { // and play run at higher speeds
    animation.CrossFade("run");
  }
}

Obviously, your model must have these animations, and you probably will have to tweak the velocity thresholds to achieve better results in your case.