// Make all rigidbodies we touch fly upwards
function OnCollisionStay(collision : Collision) {
    // Check if the collider we hit has a rigidbody
    // Then apply the force
    if (collision.rigidbody) {
        collision.rigidbody.AddForce (Vector3.up * 15);
    }
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void OnCollisionStay(Collision collision) {
        if (collision.rigidbody)
            collision.rigidbody.AddForce(Vector3.up * 15);
        
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def OnCollisionStay(collision as Collision):
        if collision.rigidbody:
            collision.rigidbody.AddForce((Vector3.up * 15))