Doing things he knows he shouldn't

[LauraP86]

Ok, So my little one is 3.5 years old and just lately he keeps doing things he knows he shouldn't and not for attention. He cant seem to help himself. " of the biggest things he keeps doing is throw stones at my car, the second he has done it he knows he shouldn't have but he just cant seem to help himself and the same with putting stones/slate/anything in our pond. He knows it could kill the fish, he tells us as much. He does it on the sly when he thinks we are not looking and sometimes right in front of us. He gets upset when told off, I have tried explaining it, discipline etc but nothing works. In other aspects he is good as gold doing what he is told etc. Just the stones thing and he know he tell us he knows he cant keep doing it but he also admits he just cant seem to now do it either. Any advise wold be amazing!