Yes, No and Uhmmmm

I was trying to figure out the lyrics to David Lafore's song Petit Oui when my ex fling/ unsure friend (now non fling/ guessing friend), told me it was about the vagueness of 'Yes' in a relationship.

It was ironic. This coming from the vaguest person I have (not) been with. In fact, while having the most intriguing chat with him regarding the implications of yes and no - he came up with his (in)famous 'uhmmmmm'. When I was (not) with him, I think I understood his 'uhmmmmms' much more than his 'yes-es' and 'no-s'.

Let's take an arbitrary situation. You asked someone you really liked out for dinner and s/he said 'Yes'.
Does that mean s/he
a) is interested in dinner and that's it
b) is interested in dinner and more
c) just hungry

If s/he's said 'No'.
Does that mean s/he
a) is really busy but interested
b) is not interested and not busy
c) is interested but does not want to seem too keen.

But - if the answer is a delicious 'uhmmmmmm' then, at least, there is a definitive possibility!