Harlem Shake (Matt and Kim Edition):
One word: WOW. Can it be beat?
If you live in Montreal - this Sunday there is a meetup on Facebook to do a Harlem Shake at Mont Royal. Click here for the details.
*Bonus: The Black Edition is hilarious but NSFW.
Update: As much as I like the Matt and Kim Edition, the underwater version is probably the best one out there for the moment: