think something up
https://gyazo.com/388439273206d640234beff2b9f6db0d
source: [そうだ！｜無料GIF画像検索 GIFMAGAZINE
3587998]
think
something
up
informal
use
one's
ingenuity
to
invent
or
devise
something.
｟米･くだけた話｠ A〈新しい事〉を考え出す, 工夫する(
invent
)
#phrasal_verb