Actually, Cascarones means "Shells" in Spanish. Learning something new everyday...
Cascarones (colorful confetti eggs) are made by first emptying the egg contents out through a hole at one end. The empty shell is then thoroughly washed and dried. The clean shell is filled with confetti, sealed with tissue paper, and dyed fun colors. Then, the best part, you get to crack it over someone's head! Good times!
And since we are on a learning kick, here is the history of the Cascarone: (via here.)
The origin of cascarones is a little muddled. The cascarone stems from the Italian Renaissance when Italian gentlemen would fill emptied eggs with beautiful perfumes and scented powder to give to their beloved. As with the pinata, the Italians allegedly got the practice, via Marco Polo, from the Chinese, who filled the eggs with powder. The practice of making hollowed-out, surprise-filled eggs moved from Italy, into Austria, France and then to Spain.
Image via ehow.com