Chris is a caffeine-o-holic. He needs it almost constantly, 24/7, both because he loves it and because he works really really long hours and needs to stay awake on his shifts. He also doesn't care where the source of the caffeine comes from; coffee, pop, just as long as its in drink form.
Also, Chris' body is so accustomed to caffeine, he is immune to the negative side effects of caffeine (stunting growth, hyperactivity, etc).