It wasn't serious—it was all done in fun.

那不是认真的，全是闹着玩的。

《牛津词典》

You can learn English in fun.

你可以在趣味中学习英语。

youdao

I'm not saying it in fun.

我讲这话不是开玩笑的。

《新英汉大辞典》

One critic calls it the first television show in a long time that is just plain fun.

VOA: special.2010.01.08

Now, this question is fun to have fun with in some ways because it's fraught with stereotypes, isn't it?

探讨南方的特点很有意思,因为这其中充满了我们的成见,不是吗

耶鲁公开课 - 美国内战与重建课程节选

We do a lot of unique things here and have a lot of opportunities to do fun things in classes.

我们的活动都很独特，课上有很多机会做一些有趣的事。

又有趣又奇特的课堂 - SpeakingMax英语口语达人

Ergonomic models are available for children in fun colors designed especially for them.

ENGADGET: Updated Android-based I'm Watch, new I'm Here GPS tracker make their debut

"It's all in fun in the end really, " says Roe, the president of the Washington-based Whisker Club who competes in the Hungarian-style moustache category.

CNN: STORY HIGHLIGHTS

"It is the idea of bringing in fun and games into a serious topic in order to try and enhance engagement, " Dr Owen explained.

BBC: Fun and games 'can save the planet'