You have two options how you can use upside down writing text in your FaceBook Status Message, one using FaceBook Application that provides backward / upsidedown / flip text features and you can also use online upside down text generator.
Using Online Upside Down Text Generator
You can googling the websites that provide online generator for upside down text / flip text. If you don’t want to googling it, just use the website below:

http://www.en.fliptext.net/
http://www.sherv.net/flip.html
http://www.upsidedowntext.com/

Open the upside down text online generator on your web browser (Mozilla Firefox, internet explorer, chrome, opera, safari or …