When I was a kid I had a best friend named Trevor. If we found ourselves on opposite sides of anything, we'd laugh and joke right up to the puck drop/tip-off/kick-off/whatever. From the moment any game started, we were bitter enemies (and knew each others weaknesses to boot!). The second the game was over, we were laughing and joking again, trading stories from the game we'd just spent ripping each other apart. I have no problem with them being friends or hanging out after the game, it actually shows good sportsmanship. DON'T DO IT IN FRONT OF THE CAMERAS. Not that difficult.