How did you come up with this crazy idea?

Anything that is too stupid to be spoken is sung.

His story was too ridiculous for anyone to believe.

If I were you, I would not have said such nonsense.

She knew better than to ask such a stupid question.

Her behavior struck me as silly.

Her ideas sound crazy.

Her foolish idea is beneath notice.

When I tried to speak to her, I always found myself too shy to do more than stammer or say something stupid.

It is absurd trying to persuade him.

He keeps a straight face while telling a ridiculous story.

He tried to laugh her out of her foolish belief.

He tried to rationalize his foolish actions.

He regrets his stupid acts.

He thought it foolish of me to go to Kyushu by bike.

He thought it foolish of me to go there by bike.

He acted foolishly.

He was laughed at for a stupid act.

What a nonsense he talks.

He refused to accept such an absurd proposal.