Keanu blunder

I was playing badminton with Alyanna and 'counting' from A to Z. Here comes Keanu and offers to be the 'counter'. So here goes:

A-B-C-D-E-F-G of which at this point he suddenly said loudly:

"Mommy, you know how to spell CD?"

Alyanna and I pretended to not know and said:

"No we don't know." "So how do you spell it?"

He stood up and loudly said: "SD"---ooops!

I guess the joke was on my little one...and we all laughed happily ever after. The end.