Nodding along when you’re lost is how you end up lost with a smile.

Nodding is a social reflex that runs faster than comprehension. It keeps the room comfortable, the speaker moving, and you politely stranded, and the smile is what makes it invisible to everyone including you. Each nod also raises the cost of stopping, because now you have agreed to several things you did not follow.

Catch the first nod that is not true and interrupt yourself rather than the speaker. Say where you stopped following, which is a short and specific thing to say. The pause costs a few seconds and prevents an entire meeting spent nowhere.