Where did the term balls to walls come from?

- One possibility is that it comes from the world of horse racing. When a horse is running as fast as it can, its balls are literally touching the walls of the track. So the phrase "balls to the walls" would mean "going all out" or "giving it all you've got".

- Another theory is that the phrase originated in the military. Balls to the wall refers to being so exhausted due to combat and adrenaline to the point one cannot feel their testicles. Balls would feel numb against wall or ground.

- Finally, some people believe that the phrase comes from the world of rock and roll. When a band is playing as loud as they can, they are said to be playing "balls to the walls".