The little boy was a real handful. He was always up to mischief.

这个小男孩真是难管教。他总是在搞恶作剧。

《柯林斯英汉双解大词典》

As they grew more mobile, we let them move freely around the house during the day, but when we were asleep we had to contain them in a large room, otherwise they'd get up to mischief.

随着它们越来越好动，白天我们让它们在家里自由活动，但当我们睡觉时，我们必须把它们关在一个大房间里，否则它们就会胡作非为。

youdao

Have you been up to mischief again?

你是不是又捣蛋了？

youdao

Classic Halvorsen mischief was to come up with a cover design for one issue that parodied Business Week.

FORBES: Sidelines

Researchers at the Black Hat conference showed just what mischief a commonly used UK PoS terminal could get up to when they inserted a chip-and-pin card crafted with malicious code.

ENGADGET: Security experts hack payment terminals to steal credit card info, play games

The resulting surge of papers revealed that the virus is vulnerable to existing seasonal-flu vaccine and common drugs, allaying fears that mischief-makers would conjure it up and wreak havoc.

ECONOMIST: Flu research and public safety