Because it is business related, you do ask the boys you take to dress nicely and look (and act) decently. Because it's July, you also ask that everyone take time to shower and clean up before the group leaves for dinner.
You have the older boys start cleaning up first, since they're actually capable of staying clean for an hour at a time. When they're mostly finished, you go outside to start running the next group of boys into the shower.
Normally, the boys get along well in the pool. They know the rules, and most follow them.
Not so much this time.
This time, you come out to find Brad picking on his little brothers.
[You must be registered and logged in to see this image.]
Not only is Brad breaking your pool rule about dunking other kids when you catch him (you don't enforce it too strictly when it's a small group of friends, but you've found it to be a good idea in larger, age-mixed groups), but both boys and one of your sons are telling him to stop, but he just keeps going, which is how you define bullying - not stopping when you're asked.
You pretty much yank Brad out of the pool. He tries to explain that he was only playing, but you remind him that it takes two people to play, so when one of them is asking (or telling) you to stop, it's no longer playing. Brad knows he's in trouble, though you do listen to him. After all, you were the oldest kid, and you know younger siblings can be pains and pests, and that they sometimes beg for trouble. He doesn't even try to make an excuse like that - he insists he was 'just playing' and that he got carried away. Considering that his younger brothers were almost in tears, you don't really find that an acceptable excuse.
His trunks are dripping, so you leave them to dry in the sun room to dry and escort him to your office. You do offer to call his dad, if he feels you're being unfair, but he seems to know he screwed up, as well as being aware that calling his dad would make him miss dinner and the movie, and that Dad has a date which he'd have to miss. Brad decides to take what he has coming and get it over with.
You give the boy a thorough spanking, then help him calm down afterwards. He still needs to get cleaned up though. While your home is fairly easygoing about nudity, he is freshly spanked, so you give him a towel to cover with, and send him to your bathroom, then you go to get him clothes.
Your bathroom is pretty big, and the shower can handle two full sized adults, so the younger boys often use it as a public shower at times like these. When you take Brad's clothes to your bathroom, you find him naked. Most of the boys are being sympathetic.
No, while standing there, drying off, with his own white, bare little bottom exposed, he's making fun of Brad. Brad is not amused to the point it looks like a fight's about to start. At least until he sees you. Brad quickly steps into the shower, but not fast enough to get Jared to leave him alone - that also happens when he realizes you're behind him.
What's a good way to nip this in the bud?