This video with the young man in the giggle shirt is Dean when he first started laughing.
Compare this video to my next post of Jack's giggling.
A conversation with Dean at 2 years old :
Dean: "Jack, That a big NO NO!" while waving his pointer finger in Jack's face for emphasis.
Me: "Dean, Jack's not doing anything wrong. You let mommy and daddy be the boss of Jack."
Dean (while looking seriously into my eyes): "No, mommy, you not boss. Daddy boss. Dean want to be boss too.