2 sentences for 疯疯癫癫 (fēng​feng​diān​diān — deranged)

1. 他受了惊吓以后，变得有些疯疯癫癫的。

   tā shòu le jīng​xià yǐ​hòu, biàn de yǒu​xiē fēng​feng​diān​diān de.

   After being frightened, he became a bit erratic.

   Source: Dong Chinese Dictionary

2. 自从遭受重大打击后，他就变得疯疯癫癫的。

   zì​cóng zāo​shòu zhòng​dà dǎ​jī hòu, tā jiù biàn de fēng​feng​diān​diān de.

   Ever since he suffered a major blow, he has become mentally unstable.

   Source: Dong Chinese Dictionary