I remember doing this when I was around the same age. Looking back and after having gone through a lot of spiritual healing from my past, I came to realize I did this as an attempt for attention after feeling rejected from my father mainly. Rejected and unprotected ultimately. Embarrassing him will not work. It’ll only make it worse.
I do not read into this as him having a disorder ,this sounds like a behavioral Issue Go to and read the thread that Broakan has left for you, and get his Dad involved in telling him it is not okay for him to behave like this.perhaps he needs attention and is seeking it in negative behavior.
My son did this too around the age of four-five. This was one of a few bizarre behaviors that cropped up over the next two years. He was still wetting the bed (still does at age seven), but had been potty trained for daytime. Pediatrician sent us to a urologist to rule out physical problems. We tried behavior modification--taking away priviledges etc. Eventually this subsided, but then other behaviors emerged. He continued to have occassional daytime accidents (could not hold it--not sneaking into a corner and peeing on his rug. Then at start of kindergarten, he acted inappropriately in the bathroom at school and started cutting holes in his clothes. He was also talking to to someone who was not there. We went to a psychiatrist in a panic--he had been such a laid back and happy normal baby and toddler. Since we were adoptive parents, we were so happy we had wound up with a child who happened to have such a good temperament.
He was diagnosed with bipolar disorder with psychosis. Our lives have been blown to bits with his illness. Things have gotten better with treatment--it takes a while to to find something that works, then of course it stops working...His mood swings are getting worse, but he does not have the one hour to three hour rages that other parents of bp kids have talked about to me.
Not saying that what your grandson has is bp, It is early to tell, He would need to be evaluated and his mother would have to discuss all of his behaviors. My advice is to get him to a behavioral specialist right away. If he is exhibting any other weird behavior, it might be the start of something more serious, and he should be watched. Not saying necessarily medicated at this point--but monitored. This was an early warning sign that we did not know about. If you have any other questions, let me know. Good luck.
Rather than punishment it would be a better thing for the child to find out why he did this,you are correct it wouldnt be a good ,or kind to tell anyone outside your selves,perhaps if you speak to him you could ask why he did it ,he may be more forthcoming to you. Has there been a new sibling , new school., anything that could make him feel some anxiety?Children feel somewhat threatened if routine is changed and they are getting less attention. I would go that route and give him extra attention,. and Dad laughs but it isnt an appropiate thing for him to laugh ,his son would take it that Dad thinks its okay, and whilst its best to find out why , has he seen his Dad do it one wonders?
I was looking for an answer on bedwetting and noticed your question. There is a complete thread of info dedicated to this subject of bedwetting that could prove helpful at:
http://www.nomorebedwetting.info/
Otherwise, my child has done the same thing a few times, as well as in a few other places in the house. 1) We told him to get to a bathroom immediately, and 2) some privileges were taken away for a time. I think we also made him help clean up. It didn't happen more than a handful of times and I think it has stopped...it's been about a year.