AFK (Away from Keyboard) is a state a pirate goes into if he or she hasn't moved in ten minutes, or alternatively types the command /afk.
Unless a continuous emote is used (like glare), the pirate will slump down and use the sleep emote, and the letters AFK will appear in gray above their head.
A pirate can get out of being AFK by moving around or clicking the screen. Being AFK can be dangerous if you are around enemies, because you run the risk of them moving and attacking you.
It can also be dangeous during the Halloween Event because the moon might become full and you will be attacked by other pirates.