Balls to the wall is an idiom that refers to a maximum commitment or effort; e.g. full throttle. It originates from aviation, in which the throttle and fuel-air mixture controls were shafts with balls on the ends to serve as handles, and pushing them toward the firewall (the “wall”) resulted in maximum fuel flow with a fuel-rich mixture flowing into the engine.
Per Wikipedia:
Balls to the wall is an idiom that refers to a maximum commitment or effort; e.g. full throttle. It originates from aviation, in which the throttle and fuel-air mixture controls were shafts with balls on the ends to serve as handles, and pushing them toward the firewall (the “wall”) resulted in maximum fuel flow with a fuel-rich mixture flowing into the engine.