okay = Everything’s cool.
okay? = You make no sense.
okay… = You’re creepy.
okayy = I don’t care.
Okay. = I’m pissed off.
Oh…kay? = that came the hell from left field.
Oh. ‘Kay. = I am now working with optimal information. Thanks.
…okay = I’m sure you needed to say that but I don’t know what to do with it.
And a family variation:
Kayo-dokeeeeeeeyyyy = I am very much punch drunk and probably already doing the thing/I have been told five times, please rack off