Caught this on Slate and have enjoyed playing it for a few people. If you're not familiar with chatrourette, it's a website that randomizes site-to-site connections. From what I understand, it's populated with weirdness, but SteveKardynal got the idea of lip syncing "Call Me Maybe" in a wig and bikini and putting together a short video of peoples' reactions.
I love the random reactions, with 80% of them being spontaneously positive and joyful. Those that aren't are still entertaining.
It's a little over the top, but it's one angle on the practice of 'being happy for no reason.'
http://www.youtube.com/watch?v=YCiY1y3uJ3o
Here's the Slate article.