// Activate the gravity of other object we touch
function OnControllerColliderHit(hit : ControllerColliderHit) {
    if(hit != null) {
        hit.rigidbody.useGravity = true;
    }
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void OnControllerColliderHit(ControllerColliderHit hit) {
        if (hit != null)
            hit.rigidbody.useGravity = true;
        
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def OnControllerColliderHit(hit as ControllerColliderHit):
        if hit != null:
            hit.rigidbody.useGravity = true