/egg is an E2 chatterbox command, short for Everything2 Easter Egg. There are no level requirements to use this command, but the user needs to have at least one "easter egg" in their inventory.
There are several methods to get easter eggs. You can try your luck at the Wheel of Surprise, which tends to give them out like stores discounting chocolates the day after Easter. Another user can give you one or more eggs, and some kind souls hand them out as a thank you for excellent writeups or for participating in contests on E2. If you decide you want to go the Veruca Salt route and insist on having an egg right now, you can always buy one in the E2 Gift Shop, on sale for only 25gp.
To use an easter egg on someone, you type in the following in the chatterbox, otherwise known as the catbox:
/egg <insert user name here>
An example would be:
/egg Dai-Un
This will make a message appear in the catbox: Rancid_Pickle eggs Dai-Un!
Additionally, the recipient will discover that they have received 3gp in their account. This message will appear at the top where their vote counts and C!'s are shown.
For those folks who are Level 15 or above, you can also use a special /egg command called /fireball. For those who wish to earn one of the oddball achievements, if you collect one hundred easter eggs you'll be granted a special one called Eggs-ellent Work.
A nodeshell rescue in honor of both Sensei and his companion, the prolific cat typist Dai-Un.