Smacking A** (Butt)

See link below about butt smacking:
https://www.youtube.com/watch?v=GaDWPlu-8d8

Why is it that butt smacking is allowed in sports between men and is not seen as being gay yet if boys/men were to smack each other butts elsewhere, they are considered less masculine or "questionable/fruity"? Why do we as a society frown upon men closeness and positive physical interaction with one another when it is one of the few times that men express something more then negativity or violence. It seems the only time it is accepted in America is when it is being cover up by a hyper-masculine costume-sports- such as with football, baseball or basketball. I feel as though we are being extremely two face when certain actions are considered acceptable in certain setting but not in others.