I also think your son would be doing this either for attention, a dare, to see if he can get away with it, ect ect. I have a 9 year old boy and he is a very good well behaved boy but I could see him doing this if he was dared, or if he really had to go!
i feel like alot of kids do this kind of thing just for attention. i also believe theres nothing wrong with him, just maybe something impulsive got the better of him.
Thanks for your prompt response, your advice is what we excatly did.
Have you asked him why he does it, what was his response,it could be a bit like a dare ,he knows its something he shouldnt do,how did you find out about it,. I dont think there is anything wrong with him, maybe some talking to and say to him that it is inappropiate and if he does it there will be no TV, PC or something else he enjoys.