Field of Dreams

I had a strange dream last night. I was talking with an unknown guy in Japanese. I wasn't sure if that guy himself was Japanese but his Japanese was of native speaker quality. My Japanese was at my current level, which means I have to think before I can make out a sentence. In a way, it was practice through pushed output. When woke up and thought about it though, I noticed something really strange. The whole thing took place in my dream, which means its all in my head. Then, how was my brain able to generate perfect Japanese for the other guy when my Japanese was no better than it is in the real world. The only explanation I could think of is, in a dream could happen. :p