Anna S sez that what drives her mental is the expression "drives me mental."

"Mental" means, innocently enough, pertaining to the mind. It is used as an adjective to indicate those things which are of or in or from the mind.

But it has acquired a colloquial meaning (probably a reduction from "mental illness" and/or "mental disease" and/or "mental defect" and/or "mental case") meaning insane, deranged, crazy, psychotic, or psychiatrically disordered. In the latter sense, it is used in expressions like "drives me mental" and "he got all mental."

As I understand the climate of the Board these days, only prescriptivists are allowed to decry this usage, and even they may not state that it drives them mental.