Many people use linetypes with words built-into them like "GAS" or "CW". When drawing with these linetypes the words sometimes appear upside down or in the wrong direction. To fix this issue, AutoCAD 2010/2011 has a new command called "REVERSE". It is located in the Modify Panel in the Ribbon or type REVERSE in the command line.
It's pretty simple to use: Reverse Command Video