It was established minutes into the pilot that Hank sells propane and propane accessories, and we learned fairly early that Dale is an exterminator. In the episode where the guys play paintball against Green Day we see that Bill is a miltary barber ( a "techie": civilian GS-types, not other soldiers, cut soldiers' hair. I have been buzzed by a few in my day). Have they ever said what Boomhauer or Kahn do for a living?
"Say hello to your mother!" "For God's sake, Daddy, she is not my mother. We went to kindergarten together!" "Hey, Hank. Do you still like to fingerpaint?"