There are already some emotional TTS voices available.
Some laugh, yawn, cry and emote with feeling.
Doc Benway (a former member here) posted a link somewhere
but I'd bet it was in the Voices section (imagine that!).
I believe the voice was named Simon. Do a search at the top
right for Simon in the Voices folder.
I don't know about the yeahhhh right thing but it certainly
is (Simon's voice) a step toward realism.
If I happen to run across it before you do, I'll post the link for you.