if someone yawns you say 'I agree'
too bad
It means that you agree to what he has said or what he or she wants.
"Can you say that again?" is a request for someone to repeat what they said. It is not a question with a yes or no answer.
When you agree, you say yes.
Pay them?
You can say phrases like "I agree," "I think so too," or "You're right."
The Cambridge Dictionary defines the phrase 'I bet' as someone say 'yes, i agree'. One could say that it is much easier to say 'you bet'. But, one would use 'yes, I agree' when talking in formal language.
No. If you are trying to say that you have the same opinion as another person, the correct way to say it is "I agree with you."
In Welsh, you would say "Rwy'n cytuno" to say "I agree."
If they say "I agree with you" or "yes" a lot, or if they nod, or if they do as you say, then it is highly likely that they understand you.
Just say I like you a lot wait for a response then give a hug if they agree