What is a "plz" account?
A "plz" account is a deviantART account where the avatar is an emote that you can use in your journals, comments, etc.
How do you use them?
To use them, write :icon(thenameoftheaccount):
An example is :iconsupertighthugplz: which is written as :icon supertighthug plz: (minus the spaces)
Some popular accounts are:
To get the account name, roll your mouse over the image and copy the text you see beginning with an :icon and ending in a :.
Quick lesson in dA