“Spawn camping” is a term used in video games. When an enemy player is killed after a certain amount of time they “respawn” or reappear in the game usually and certain fixed locations. Some experienced players know the spots where this will happen and “camp” or wait for the newly respawned player to appear and surprise them to get an easy kill. In this meme, the ghostbusters are spawn camping because they’re somewhere where a child will likely die and become a ghost and they’ll be right there waiting to catch it.