疯狂 (fēng kuáng): crazy, insane

In order to prepare for the college entrance exam, he studies until 3 a.m. every day—it's simply crazy.

The fans rushed madly onto the field, wanting to take photos with their heroes.

She fell madly in love with that rock singer, and even followed him to another city.

This restaurant's business is crazily good; the queue stretches from one end of the street to the other.