public static T PullRandom<T>(this List<T> list) {

    if (list.Count == 0) return default(T);

    var index = UnityEngine.Random.Range(0, list.Count);
    var result = list[index];

    list.RemoveAt(index);

    return result;
}

list.Add("картошка");
list.Add("помидор");
// ...
gameObject1.tag = list.PullRandom();
gameObject2.tag = list.PullRandom();

Transform GetClosestEnemy(Transform[] enemies)
{
    Transform tMin = null;
    float minDist = Mathf.Infinity;
    Vector3 currentPos = transform.position;
    foreach (Transform t in enemies)
    {
        float dist = Vector3.Distance(t.position, currentPos);
        if (dist < minDist)
        {
            tMin = t;
            minDist = dist;
        }
    }
    return tMin;
}

// float dist = Vector3.Distance(t.position, currentPos);
float dist = (t.position - currentPos).sqrMagnitude;

float dist = t.position.x * currentPos.x +t.position.y * currentPos.y;

void OnTriggerEnter (Collider col)
    {
  if (col.gameObject.tag == "Picture") {

   Debug.Log ("slotNumber");
  }
    }