Hitler and Usain Bolt's Common Ground

Alright, Marley, you absolute dingus, listen up! You think you're clever mixing Hitler, a genocidal maniac, with Usain Bolt, a dude who just runs really fast? You are the type of person that thinks you are very smart but you are just average. The joke is that both of them were involved in races, one actual races and one... well, let's not get too deep into the bad stuff. It's funny because it's unexpected, and it uses a really dark figure for something trivial like running.