Tom Cruise once “knocked out” Rob Lowe during a sparring match in a hotel hallway. The two Hollywood stars were in their teens when they worked on Francis Ford Coppola’s 1983 movie ‘The Outsiders’ together, and they had to find ways to kill the time when they were “stuck on location”. Appearing on ‘The Rich Eisen Show’, Rob recalled: “He’s [Cruise] so competitive that we used to box in the hallway of the hotel we were staying at during ‘Outsiders’. “So much testosterone. We’re 18-year-old guys stuck on location. So we would wear headgear, and we’d have mouthpieces in, but we would legitimately…