Listening to my coworker on the phone, saying "OK" a lot, made me think of the word. I was able to follow what each OK meant by the way she was saying it. There's the "OK" of "I'm sure what you just said makes sense but I can't process it," the "OK" of "Yep, got that one, next item...?", the "OK" of "Yep, I'll call again if I have any problems, and we're about to hang up", etc.
So...what other words are versatile like this? Where depending on how you say them it's clear to others what you mean beyond the definition of the word. Another one that comes to mind is "really".
"Really?" - "is that really true?"
"Really?" - "Oh, you think so, huh? Whatever."
"Really!" - I shit you not!
"...really..." - "very"
Yeah. I'm bored. :)