It starts innocently, as teammates helping each other out.  The little jock made a comment about a sore shoulder.  Big jock offered a shoulder massage with shampoo to make things slick.  As the shampoo runs down his back it collects in his hairy ass crack.  This allows the big guy to “accidentally” slip his cock into the little guy.  Just a little push on those shoulders and the little guy is bent over taking it up the ass, almost as though he planned that way.