Formal:
* 流氓 (liú máng): This is the most literal translation of "rascal" and refers to a hooligan or a person who is dishonest and behaves badly.
Informal:
* 淘气 (táo qì): This means "naughty" or "mischievous" and is often used to describe children who are playful and mischievous.
* 小滑头 (xiǎo huá tóu): This means "little slicker" or "sly one" and implies someone who is cunning and mischievous.
* 顽皮 (wán pí): This means "naughty" or "impish" and is often used to describe children who are playful and rebellious.
* 调皮 (diào pí): This means "naughty" or "mischievous" and is often used to describe children who are playful and mischievous.
The best translation will depend on the specific context and the kind of rascal you are trying to describe.