OnTriggerEnter is called when the Collider other enters the trigger.

This message is sent to the trigger collider and the rigidbody (or the collider if there is no rigidbody) that touches the trigger. Note that trigger events are only sent if one of the colliders also has a rigid body attached.

	// Destroy everything that enters the trigger
	function OnTriggerEnter (other : Collider) {
		Destroy(other.gameObject);
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void OnTriggerEnter(Collider other) {
        Destroy(other.gameObject);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def OnTriggerEnter(other as Collider) as void:
		Destroy(other.gameObject)

OnTriggerEnter can be a co-routine, simply use the yield statement in the function.