Before I begin, I swear to God I am not making this up
One day, I was with some friends at a park in Minoh, a wonderful little city north of Osaka. This park, Minoh Park, is set in the mountain woods, and is famous for its monkeys, who live in the trees and occasionally swoop down to say a quick monkey "Hi!" to the tourists.
Now, monkeys are wily and dexterous creatures: heck, you would be, too, if you had a prehensile tail. So, when you go to Minoh Park, there's a big sign at the beginning of the nature trail that warns you about the monkeys. It shows you how they might try to steal your picnic basket or torture your children, complete with full-color illustrations.
Anyway, we didn't actually see any monkeys on the trail. The real amusement came when we reached a waterfall in the depths of the park, adjacent to a snack bar and some public toilets. Inside each restroom, there was a big red button, sort of like the emergency shutoff button you would see in a chemistry lab. Next to each button was a little placard that said (roughly) PUSH IN CASE OF MONKEY ATTACK, and a graphic of a monkey beating the crap out of a person sitting on a commode.
Curious, one of my friends decided that he would see what the monkey alarm would do. So, while we waited giddily on a nearby foot bridge, he ran into one of the bathrooms and hit the button. All around us, klaxons began going off: BUZZ! BUZZ! BUZZ! BUZZ! Terrified, our friend ran back to where we were hiding, and we all watched together, waiting for some scene of mass panic to unfold.
Several minutes passed, and nobody came. Eventually, the klaxons stopped. So the monkey alarms were ultimately ineffective, leading us to conclude that the monkeys have already won.
Sasha Gabba Hey! postulates that the monkey alarms may be intended to scare the monkeys. I would argue that the park rangers were scared of having to fight off a monkey invasion, and after seeing The Wizard of Oz, I'm inclined to agree with them.