Kevin Hart and Conan O'Brien [1] both have jokes that could keep us laughing for days, but we don't think Conan was laughing after going head-to-head in the gym with the hilarious, yet incredibly fit Jumanji actor. On Sept. 29, the two comedians worked out their important muscle groups and their witty disses during a skit on Conan's show, but it was all fun and games until Conan needed a boost during pull-ups [2]. "Get under my ass!" he demanded. "A little boost or I won't promote your f*cking movie!" That's all it took to get Kevin under there. They worked out with medicine balls, punching bags, and enlisted some trainers for help [3], but even they couldn't save Conan. Watch the video and see what happens when two comedians face off in the gym.