Meaning:

“皮” is short for “调皮,” which means “naughty,” and “一下” means “for once.” A dialect word often used by a popular gaming commentator by the nickname “wuhu dasima,” this term caught on among netizens recently. Many people use the phrase after they’ve said or done something funny as a means of depressuring. They also say “皮一下很开心.” (Literally: “I feel happy to be naughty for once.”)

Example:

A: 六一你出去玩了吗？

Liùyī nǐ chūqù wán le ma？

Did you go out to have fun June 1?

B: 谁这么大年纪还过儿童节啊？

Shuí zhème dà niánjì hái guò értóngjiē a？

Aren’t we too old to celebrate Children’s Day?

A: 我去了新开的乐高专营店，皮一下很开心。

Wǒ qù le xīn kāi de lègāo zhuānyíngdiàn，píyīxià hěn kāixīn。

I went to the newly-opened Lego shop. It’s a lot of fun!