Aside from just dealing with zombies on a daily basis, the apocalypse brings out the worst in other people. Want to figure out if a newcomer is worth keeping in your group, or if he is liable to murder you in your sleep? Sodium pentothol is definitely your friend, as it is often used as a "truth serum." Essentially, sodium pentothol, or sodium thiopental, can be used as a truth serum because it lowers the recipient's higher brain function. Because lying is a more mentally exhaustive process than just telling the truth, it has been shown to work pretty effectively as a truth serum. Definitely an asset if you want to weed out the weirdos from your team of survivors!