Jammy is talking to his grandparents on the phone......
Grandparents: Blah..blah..blah... (grandparents say something on the phone, obviously asking Jammy a question)
Jammy, responding in the affirmative: nods silently
Alfie, beside Jammy: No Jammy, they can't see you nodding, you have to say it out loud.
Jammy: Nana, I'm nodding.
(and for the rest of the conversation, instead of answering Yes to his grandparents' questions, Jammy would say, "I'm nodding").