Silly

つまらない

tsumaranai

(playful, giggly)

他愛ない

tawainai

(foolish, showing a lack of good sense and wisdom)

愚鈍

gudon

(pejorative: simple, not intelligent, unrefined)

阿呆

aho

(irresponsible, showing irresponsible behaviors)

阿呆

aho

(pejorative: simple, not intelligent, unrefined)

馬鹿

baka

(foolish, showing a lack of good sense and wisdom)

馬鹿

baka

(irresponsible, showing irresponsible behaviors)

馬鹿

baka

(pejorative: simple, not intelligent, unrefined)

馬鹿げた

bakageta

(foolish, showing a lack of good sense and wisdom)