Six Year-Old Won't Stop Laughing During Punishment / Talks

Hello all,Recently my SO's 6-y.o. middle child (I am not the father, though the child in question calls me daddy and tends to relate to his biological dad moreso than his brothers) made a lewd comment about his private parts around his brothers that required reprimanding, and when it came time for us to talk to him about why he said that and the fact that kids his age should not be saying stuff like that, he would not stop smiling as we spoke.My SO told him to stop or she would wipe the smile off his face, and she gave him a light smack on the lips with her fingertips. However, this action did nothing but cause him to laugh out in what seemed to be pleasure, as if he liked being punished in that way. Eventually, he was sent to his room for the night, as I decided he would get no attention instead of the negative attention he seemed to crave.While I'm aware that some children smile in the wake of punishment, perhaps as a defense, this smile seemed to be out of pleasure at being punished, and I don't know what I can do besides give him no attention at all, which doesn't seem to be a good course of action. He is disruptive towards other kids at school and at home with his brothers, and we frequently have to take corrective action over naughty things he either says or does. He also thinks that, whenever he gets in trouble with us, that his brothers are "just trying to get him in trouble", and doesn't seem to understand that his actions are what led to others telling on him and thus bringing on corrective action. I should mention he has been diagnosed with ADHD and takes the lowest dosage of medication that he can, if that impacts the situation at all.Him laughing during punishment is not anything new, and he has told us that he has given up on being a good kid, even though we tell him he is a good kid and make an effort to reinforce positive behavior. However, it seems like we just keep telling him not to do the same things over and over again, and it gets tiresome repeating ourselves when the kid doesn't seem to want to make the right choices.When I said he tends to identify with his father, I say that because his dad does whatever he wants with no regard for others' feelings or plans, belittles (for example) fat or people of minorities in front of his kids (even going so far as to tell the kids Donald Trump is going to send black people back to Africa), and tends not to have respect for authority. We see the child's behavior as a reflection of his father's. I don't know if this is an accurate read of the situation.I truly love and care about this boy, and I do not want him to develop a complex as "the bad boy". We tell him he is a good boy, but that he makes naughty choices, but after seeing the look on his face as he enjoyed his punishment, I am at a loss as to how I can work with this kid and try to discourage him from making naughty choices. If I'm being honest, his face and his reaction disturbed me and my SO.I guess my question is, when the child only laughs at us when he's being punished, and doesn't change his behavior after we talk to him, what is best to both correct the naughty behavior and do right by the kid?Any insight is appreciated. Thank you. via /r/Parenting http://ift.tt/2a39sPS