How bouncy is the surface? A value of 0 will not bounce. A value of 1 will bounce without any loss of energy.

	collider.bounciness = 1;

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        collider.bounciness = 1;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		collider.bounciness = 1