This objection is often presented with a type of "stump the Christian" attitude.
Dr. Norman Geisler and Ron Brooks demonstrate the fallacious thinking that grounds this type of objection in sinking sand:
"This is... (a) meaningless question. It asks, "Is there something that is more than infinite?" It is logically impossible for anything to be more than infinite, because infinite has no end. The same applies to questions like, "Can God make a square circle?" It is just like asking, "What is the smell of blue?" It is a category mistake-colors don't smell and circles can't be square. These are logical impossibilities. God's omnipotence does not mean that He can do what is impossible, only He has the power to do anything that is actually possible, even if it is impossible for us. Any mountain that God makes, He can control, put where He wants, and disintegrate if He likes. You can't ask for more power than that." 
Courage and Godspeed,
1. Norman Geisler and Ron Brooks, When Skeptics Ask, p. 30-31.
For further research, see the following:
1. Can God Create a Rock So Heavy He Can't Lift It?- Can God Truly Be Omnipotent? by Rich Deem
2. Things God Cannot Do by Let Us Reason Ministries