Go to
http://trollmegle.cel3stial.com/
Start a conversation.
Ask "What is OP?"
If you get anything except "a faggot", you have encountered a regular citizen. Tell them to get indoors.
If you get a roleplayer, however, you have encountered a zombie. Kill it (-1 shell).
You start with and have a maximum of six shells.
If they answer "a faggot", you have encountered a fellow survivor and get the starting six shells again.