The meme brilliantly combines two classic computer science nightmares: the Traveling Salesman Problem and the Trolley Problem. In one, you're trying to find the optimal path through a complex graph (a famously NP-hard problem that makes algorithms cry). In the other, you're deciding which track to send a runaway trolley down, usually with moral implications about who gets squished. The joke is that instead of optimizing for the shortest path or making a moral choice, our protagonist is choosing the path with the most people to run over. It's basically what happens when your pathfinding algorithm has a vendetta against humanity. Dijkstra would be horrified... or impressed, depending on his mood that day.