Pee Pee

E. is fully potty trained, but we are working on staying dry during bedtime.  He is 3 years and 4 months old.  Lately I have been putting a diaper or pull up on him at night, to keep bedding dry.  Last night J. put the boys to bed and decided to have E. sleep in his big boy underwear.  He woke up, changed his wet pants by himself and started to play.  We went to his room to grab some clothes and noticed a huge puddle of urine on a bean bag chair in their room.  We questioned E.  He acted out the whole thing very clearly, showing us how he pulled his pants down and went "pssss" on the bean bag.  He got in BIG trouble.  He was asked where he should go pee pee.  He replied "in de toilet".  This is in fact the third time he has urinated in his room on purpose.  I am not very happy and am not quite sure how to discipline.  Even negative attention is attention, if this is why he is choosing to do this.  The bathroom is a quick few steps down the hall so I don't think it's that he couldn't make it there.  I think that part of the problem may be that at the o. the boys would urinate wherever they chose to outside.  Maybe.  Or maybe he is just doing this to be naughty?  I don't know.  Hoping he will not do this on our camping trip this weekend! Now, off to do some laundry, pack and clean up pee pee.