Discuss discipline before playdates.
Disciplining another parent's child can land you in dicey territory, so you should consider discussing the topic with the parent beforehand. Ideally, you should be comfortable reprimanding a kid who steps out of line when in your home. If he does something unacceptable, simply remind him that it's not okay in your home, and if he wants to continue playing, he'll need to obey the rules of your house. If need be, it’s completely acceptable to end a playdate.