(idiomatic) To exert an unrestrained, aggressive effort, especially by assailing an opponent's or victim's area of greatest vulnerability.

present participle of go under

(informal) To lose one's sanity. / (informal) To have a good time, free from restraint.

(UK) daring, courageous, particularly in the face of unexpected adversity.

present participle of go poof

(informal) to disappear

To alternately enter and exit, arrive and depart (either physically or figuratively) / To repeatedly appear and disappear; to be transient

To suddenly behave irrationally; to go mad.

(idiomatic) To be available but wasted, unused, or not actualized.

(archaic, law, of crops) Sown during the last years of a tenancy, but not ripe until after its expiration.