How Words Work

We gave BSM a child-friendly camera for his birthday, and he's been enjoying it mightily. This morning, he asked me how to get to a particular feature, so I showed him how to select it. However, before instructing him to push the final button in the sequence, I paused to teach him something useful about that button.

"Hang on," I said, and pointed to the "OK" button. "What letters are these?"
Hurrying to get to his feature, BSM distractedly said, "Letters."
"Yes, but which letters?" Pointing to the O, I asked, "What's this letter?"

Actually looking this time, BSM said, "O."

"That's right. And what's this one?" (Pointing to the K this time.)

"K."

"Right. So what does that say?"
"Camera."
Good guess. Smart kid. Clearly understands about words being made of letters and forming abstract representations of real-world concepts. 

"Not quite. This letter's an O and this letter's a K. That's an O and a K. O-K. What word is that?"

Eyes lighting up, BSM crows, "OK!"

"Exactly! So once the screen shows what you want, you push "OK". All right? Got it?"
Reaching for the button, BSM responds "Okay," and immediately cracks up without any prompting on my part. Yay, getting jokes and wordplay!