If "God" is so powerful, then can "God" make a boulder that "God" cannot pick up?

If God exists, then it would be physically possible. Think about it. If He gets bored and created boulders out of thin air, and makes Himself tiny, then, at the time, He would not be able to lift said boulder. Assuming that He WANTED to make Himself succeptable to physical laws. It's all up to Him. That omnipotence problem is easy. It gets a little hairy when ones asks it God can make Himself not God, erase His own memory, and things along those lines.