in fun

例句：

1. 1.She was playing with her friends in the park, in fun.
   她和朋友在公园里开玩笑。
2. 2.They were joking around in the kitchen, in fun.
   他们在厨房里开玩笑。
3. 3.I like to play games with my friends in fun.
   我喜欢和我的朋友们开玩笑玩游戏。