The torque - relative to the rigid bodies coordinate system - applied every frame.

	// Rotates the object around the its own x-axis
	constantForce.relativeTorque = Vector3.right * 2;

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        constantForce.relativeTorque = Vector3.right * 2;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		constantForce.relativeTorque = (Vector3.right * 2)