If you think you have seen it all with McCree's ultimate then you have to watch this video. McCree was right next to Winston as Winston's ultimate goes off but goes flying in the distance. Instead of falling back down to the ground, McCree capitalizes on the situation in the only way a McCree can.
The few reactions you could possibly have to this is to slowly shake your head in amazement or scream expletives. Even if you are on the enemy team you really can't be mad at that. But rest assured this exact situation pretty much never happens. At best, McCree gets to a higher position away from enemy eyes to eliminate a decent amount of people. But to achieve orbit from Winston's ultimate and have your McCree ultimate is extremely rare.