嬉笑不是happy and laugh，这里是指嘲讽，用嬉笑的方式嘲笑或骂，怒骂，生气的骂。

I guess this might help as well http://chengyu.game2.tw/archives/53015#.Well5FuCyUk for your reference

Hi Darian, If translate it in Chinese respectively, “嬉笑” means happy and laugh, “怒骂” means angry and curse. When combine together, "嬉笑怒骂" shows varieties of different emotions and relative behavours. It is used to describe a stimulating style of writing which makes even merry laughters and angry shoutings. For example, "嬉笑怒骂，皆成文章" If you have any other question, please feel free to contact my wechat: [email protected]

出自宋·黄庭坚《东坡先生真赞》：“东坡之酒；赤壁之笛；嬉笑怒骂；皆成文章”。用来称赞不论什么题材和形式，都能任意发挥，写出好文章来。

It is means many of your attitudes towards the world, life.