1) A story with which to scare little Mexican children.
2) If said correctly, like a spooky tone, it scares the shizz outta you!
3) Basically the Mexican Boogeyman/the fucking scariest thing on the face of the earth.
1)"Si no te calmas, el Cu-Cuy te va ha agarrar!"----translation----"If you don't behave, the Cu-Cuy will get you!"
3) Say this in the dark with a bunch of Mexicans (mostly kids) and they WILL start to cry.