How to use yield return new WaitForSecond because i cantuse it on OnMouseUp

using UnityEngine;
using System.Collections;

public class Trivia : MonoBehaviour {

public static bool eel = false;
public 	float timer = 0.0f;
// Use this for initialization
void Start () {
}

// Update is called once per frame
void Update () {
	
}

void OnMouseUp()
{

if(eel)
	{
		showStuff();	
	}

}

IEnumerator showStuff() 
{
  Texthints.textOn = true;

  Texthints.message = "Correct ~!!";

  yield return new WaitForSeconds(2);

  Texthints.message ="Did you know hahahaha";
}
}

Should be:

StartCoroutine(showStuff());