AudioSource.PlayOneShot  

// Play impact audio clip when colliding with something
var impact : AudioClip;
function OnCollisionEnter () {
    audio.PlayOneShot(impact);
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public AudioClip impact;
    void OnCollisionEnter() {
        audio.PlayOneShot(impact);
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public impact as AudioClip

    def OnCollisionEnter():
        audio.PlayOneShot(impact)