ばかばかしい
ばかばかしい · bakabakashii · JLPT N1 · noun
stupid
baka-baka-shii: 'baka' (fool) doubled, plus -shii, so 'fool-ish, fool-like'
ばか (baka) means fool, and ばかばかしい repeats it to mean 'foolish, ridiculous, not worth the effort'. The -しい ending means 'having the quality of', so it's 'fool-like'.