The guys were watching an episode of John Doe on the TiVo; at some point Mista Doe mentioned that a chemical found in some drain cleaners (copper sulfide?) mixed with lemonade powder creates a reaction hot enough to melt steel.
There's no disclaimer at the beginning of the show imploring the at-home audience to stay away from nasty chemicals (because the actors are professionals, yo) so naturally Jonathan and Clayton wanted to try it. They only dug up a bottle of generic Drano that included two different active ingredients, but they're still set on using it. I try to explain that different reagents will produce different reactions, but they'll hear none of it. All they respond with is "We're melting steel!" Last I knew they were headed outside with a styrofoam cup and their reactants; we'll see if they escape the inevitable deadly fumes.