How do babies know what the word 'say' means when you ask them to say mama or dada?

When you ask a baby to "say mama" or "say dada", how come they never say "say"

This is a three-panel stick figure meme using the popular 'blow my mind' format. First, a cheerful stick figure asks the other character to blow their mind. The second character looks skeptical while thinking, then reveals a surprising trivial observation: when adults ask babies to 'say mama' or 'say dada', babies never repeat the word 'say', implying they understand that 'say' is an instruction, not the target word they are meant to speak. The joke highlights the unspoken, underrecognized language comprehension skills that babies possess, a small counterintuitive fact that feels like a mind-blowing realization most people have never considered before.

This meme was originally shared on Reddit meme subreddits, with the original post title being 'How do they know what the word say means?!'. It uses a widely circulated pre-existing stick figure 'blow my mind' meme template that is commonly used to share unexpected, trivial, or counterintuitive observations that surprise viewers.