Alternatively, it's used for self-reference by women who want to indicate their own idiocy but, communicating online, cannot visible slam their face into a wall.
Im justa reglar gurl!!
It is spelt 'gurl' rather than 'girl' because it is not a real girl, but similar enough to imitate.
Usually used in writing for context rather than spoken.
Used commonly by transgendered people in transgendered literature, but not exclusively.
He stepped into the room dressed as a girl for Halloween.
"Gurl you look hot!" said his friend.