Friend: Hey, wanna race home?
Orphan: What home?
Friend: Hey, wanna race home?
Orphan: What home?
Alright, listen up, you chucklehead! You know orphans don't have parent, right? And if you do not have parents, you don't have no home. So the friend asks the orphan to race "home," but the orphan does not HAVE a home, making the question kinda sad and funny at the same time. It's dark humor because it makes light of a sad situation, you simpleton!