Quoting ~Manda Panda +3 ~:" He just either says I don't know or Cuz I want to. He doesn't get in trouble for peeing the bed, but ... [snip!] ... the bed, but he gets in trouble for lying about it. He will get up and change his clothes thinking we won't know he did it."
Yeah lying, and hiding it isnt ok, just make sure he really understands the difference. Usually when they hide it, its because they are scared to be introuble, or they are ashamed of it. My best advice is to buy the plastic sheets to protect the mattress, and just keep working with him and washing his clothes. Cut drinks off at 6:30, and get him up up go pee again before you go to bed, or at midnight. Try for a specific time, so it will start to be routine for him to wake up and go pee. I know some kids are just so knocked out that they dont feel the urge to go, and end up wetting the bed. I would also talk to his doctor about it, just incase it is a physical/mental problem. Good luck!!