It means: Ah know, raht!
Texan for 'I know, right?'
It is not very commonly used, see below for an example (that, of course, I wrote myself. I work as an author.)
"Man, work sucks!" one of the boys cried, looking up from his shovel.
"Akr," said a woman perched on the fence and watching them sweat the day away. "Now get back to work, or I'll slap you silly."