If you are a Batman fan, or you need his help and you want to signal for him via Facebook, you can do so using the Batman symbol. There isn't a special character code for the bat signal like there is for a smiley face or a heart, so you will need to use an actual picture of the Batman symbol and the help of a special Facebook application that will make that possible.
Go to the "Status Symbol" Facebook application (See Resources) and click on the "Go to Application" button on the left of the page. Under "Request for Permission," click "Allow" to start using the application.
Download a picture of the Batman symbol (See Resources) to your computer by right-clicking and on it and selecting "Save Image As." Go to the Status Symbols app and click on the "Status and Send" tab near the top, if it isn't already selected, and click on "Choose File." Find the image of the Batman symbol that you downloaded and click "Open." The symbol appears in the window on the left of the application.
Type in anything else that you want to say in your status update in the text box to the right of the application and click "Set Status." Click "Publish" in the preview box that pops up to publish your status on Facebook. The Batman symbol that you uploaded appears, under the words that you typed, on your profile.