If you're happy and you know it, clap your hands. If you're not happy and you know it, press play on Le Youth's "Clap Your Hands" and watch that frown turn upside down in a nanosecond. By Kat Bein If ...

If you wanted to applaud Chinese president Xi Jinping's recent speech but got stuck in traffic or were halfway around the world, well, there's an app for that now. Chinese internet titan Tencent has ...