I don't have any balls?!?

One of my students uses a voice output device (here is a sample of a simple voice output device Go Talk 20) to communicate a large part of the time. We use it a lot during learning activities and he is learning to identify objects by color (i.e. purple crayon, red block) and say complete sentences (I have a purple crayon. I want a purple crayon. I see a purple crayon.). He recently started working on a new device that we are testing out that allows a lot of choices to be presented to him. Previously he could only have eight items presented, which meant it was limited in what he had to discriminate between when I asked him a question and in what he could request. So I brought along his new device and his items that we had been working with on his home visit on Friday. We were plodding along working on colors and objects (he was not in the mood to cooperate - I don't blame him, after being in school for 3 hours I don't think I would appreciate having the teacher show up at my front door with more work either). He picked up his device and began to insistently push the picture symbol for the toy ball that we had played with in class. Without thinking out of my mouth tumbled the words "I'm sorry, I don't have any balls." Oops. I froze, not knowing if his mom would want to laugh as badly as I did or if she would not appreciate the humor of the situation. Later when she cursed as she tried to put the cover on his self-opening scissors (which is a lot harder than it sounds) I swallowd another round of giggles. Maybe it is a good thing he can't imitate what we say? At least that day it was!!