Final answer:
A Shrinking Charm is a spell used to decrease the size of objects or creatures in the Harry Potter world. In the second year at Hogwarts, students used a Shrinking Charm to enter the Chamber of Secrets by shrinking themselves and going through the pipes.
Step-by-step explanation:
In the world of Harry Potter, a Shrinking Charm is a spell used to decrease the size of objects or creatures. It is not possible to physically sneak into a place using a Shrinking Charm since it only affects the size of objects and not the ability to enter a location without being detected. However, in the second year of Hogwarts, the students did use a Shrinking Charm to enter the Chamber of Secrets by shrinking themselves and going through the pipes.