Tears of joy - The most commonly used emoji on the planet, this was the Oxford English Dictionary's word of the year for 2015. What does it mean? That depends on your perspective. It could be straightforward, a person laughing so much they're crying. It could be self-deprecating - you're laughing at yourself and a silly thing you did. Or it could be a way of gloating at somebody else.
Source: 董静 & 丹妮 from language.chinadaily.com.cn