Pandemonium is chaos, total and utter craziness — like the stampede after your team won the championship, when everyone spilled onto the field at once, bouncing off each other.
If you look carefully at the word pandemonium, you’ll see the word demon inside it. This makes sense, since the word pandemonium was coined in Milton’s Paradise Lost, where it was the name of the palace built in the middle of Hell. Milton wrote back in the 17th century. Nowadays, pandemonium crops up whenever journalists are describing a chaotic scene. High school students have been heard to use it to describe their lunchroom.