Symbolism, Imagery, Allegory
So there's this high school kid named Orest Mercator, and he's only got one wish in life: to sit in a room full of poisonous snakes longer than anyone else ever has. Heinrich Gladney is a pretty big fan of the whole idea, because breaking world records is cool. Jack Gladney, on the other hand, thinks the whole snake room thing is stupid, and he tells Orest so by asking, "Do you understand that you are risking death for a couple of lines in a paperback book?" (27.48).
DeLillo uses this room full of snakes to show just how differently Jack and his son Heinrich approach life (and death). Heinrich admires his friend Orest for showing so much determination and setting a goal for himself. Jack, though, can't get past the thought that Orest is risking death for a completely stupid reason. He accuses Orest and Heinrich of thinking "death applies to everyone but [them]" (27.58). But this isn't the case. Heinrich and Orest just think that death is pretty meh. If it happens, it happens.
Through Jack's reaction to the snake room, DeLillo shows that American adults obsess way too much over death. Being practical is all well and good, and a room full of snakes might not be the best way to die (or live, for that matter). But Jack, like many American adults, needs to calm down a little and stop obsessing so much about his fear of death. He needs to accept that different people think about death in different ways, and that a crippling fear of death translates directly to leading a crippled version of life.