I’ve watched this video on youtube I don’t know how many times, and I laugh harder each time. One of the comments on the site basically sums it up: “I can’t decide if this is cute or creepy.”
(Another comment: “Are they vying for world domination?”)
Wow, I thought no laughing baby would be funnier than this guy: http://www.youtube.com/watch?v=hm2UMlKWQLA But those quads may have just taken the title.