For a playful, mischievous child:
* Masungit (means "grumpy" but can be used playfully for a child who is being naughty)
* Pasaway (means "disobedient" or "rebellious")
* Makulit (means "annoying" or "pesky")
For someone who is behaving badly or immorally:
* Masama (means "bad")
* Maloko (means "foolish" or "silly")
* Walang modo (means "mannerless")
* Bastos (means "rude")
For something that is inappropriate or forbidden:
* Hindi nararapat (means "not appropriate")
* Ipinagbabawal (means "forbidden")
For a playful, flirty connotation:
* Malilimutin (means "forgetful" but can be used playfully to suggest someone is forgetful about their clothes)
The best word to use will depend on the specific situation.
It's also important to remember that language can be subjective and there might be regional differences in how "naughty" is expressed in Filipino.