Hey, it made me sad that creationists wouldn't throw down the gauntlet here and attempt to debate you, so I'm going to go ahead and play devil's advocate here. I think the problem is the way you worded it. You told them to "disprove evolution" which is really an unreasonable task. A task just as unreasonable as me asking you to "prove evolution". How about we decide to provide evidence instead. Instead of using the creation of the universe as a preface for this argument, let's skip ahead to the beginning of life. As a creationist to this argument, I say that God created the creatures as they are here now. Life is so complex, that "intelligent design" is a logical conclusion serving as the only valid explanation for the otherwise unanswerable question of where life came from. When you establish what your argument is predicated upon, we can discuss that further. As far as evolution is concerned, it is simply illogical when you trace it back to its origins. It is easy to say that things evolved to fill niches, but what did they evolve from? What forced them to evolve? Take, for example, the difference between mammals and birds. Birds lay eggs and walk away. Mammals, on the other hand, must nurture and care for their young, expending a great deal of effort. It seems to me that the bird method is superior in just about all ways. Without a biological contract to care for the young, an individual is free to reproduce more often, creating more offspring with the potential to succeed in doing the same. This continuity of existence is the premise for evolution. Evolutionary speaking, this method would make more sense if it weren't for the fact that eggs were vulnerable when left undefended. Therefore, evolution would select for thicker and stronger eggs until they simply could not be broken prior to hatching. Logically, using the evolutionary thought process, egg-laying would be the dominate form of birthing. This was just an example of course, but evolution pins creatures against each other. In predator-prey relationships, evolution pins them against each other in an evolution contest. For example, prey could develop digging as an escape tactic while the predator could develop speed to catch them before they dig to safety. Eventually, one mutated freak in the species would be unreachable by the best of predators. This freak would reproduce and would lead his species to safety underground while the predators would go extinct after years of decreasing success with the one mutated freak's offspring. Predator-prey relationships would, logically, fade from existence. However, we see them still today, balanced as god intended. If the species change because of evolution we would see this perfect harmony disrupted, however, it is not because the predators and the prey each match each other by culling the weak and finding new weak to fill the void. Your move.