A child in diapers smears pieces of bowel movement in places such as the bed, walls, or bathroom. Rather than being deliberate to offend the parents, this behavior usually arises from a chance discovery. A bored child, perhaps one who is left in bed too long, discovers bowel movement in his diaper and decides to paint with it. Unlike parents, a child is not usually repulsed by the act of touching bowel movements.
Tell your child the rule: "Don't get any poo-poo on your bed or the walls. Poo-poo is messy. Poo-poo goes in the toilet."
Without yelling or showing anger make it clear to your child that you do not approve of what he has done. Clean up your child without any entertainment or conversation. Then clean the room, with your child's help if possible.
Avoid any physical punishment. If you overrespond the first few times your child does this, you may start a power struggle. Your child may persistently smear bowel movements to prove he has some power.
If you are toilet training your child, pressure him less about his toilet performance.
Praise your child for telling you when his pants are full and he needs to be changed.