Does your friend’s child behave badly when he is at your place? - at times he is even violent. But how do you tell his parents that you are having problems with him?
Before you actually decide to do something, ensure that whatever the child has done (like hitting or bad language) is a regular occurrence.
For most parents, even a hint regarding their child’s behavior is enough to make them take notice. But some parents can react negatively to these suggestions. Make them understand that you are not playing a blame game, but you are concerned about the child’s behavior. If his behavior does not improve, keep your child away from him.