Lost in Translation

I thought I understood how to speak 4 year old.  Sometimes we have these strange communication blips and I get odd behaviors that surprise me.  I think my communication seems clear and well, I guess it gets lost somewhere between my mouth and his ears.

For instance-

Mama: Go put your shorts and underwear on.
Nas: Where is my shorts and underwear?
Mama:  You took them off in the bathroom before nap.
(He sleeps in a pull up)
Nas: I don't know where they are.
Mama: In the middle of the bathroom.

So he goes into the bathroom and shuts himself in for several minutes.  When he emerges, he is completely naked.

Now, he can't find the shirt that he was wearing when he went into the bathroom.