小逗比小任性
[xiăo dòu bĭ xiăo rèn xìng]
Both '逗比(dòubǐ) 'and '任性 (rèn xìng)' have the same meaning which refers to someone who's naughty, cute or being stubborn and self-willed in a lighthearted way, so this user-name reflects that he likes behaving freely and playfully, doesn't care too much what others think, and wants to show that side to all users. It is also quite colloquial in language and gives a friendly atmosphere.