I think it was in this thread that someone questioned the meaning of "hey" in a setence such as "I want you to understand--hey--this is not rocket science."

Seems to me this a sort of verbal equivalent of an exclamation point. The exclamation point, though we often loosely call it punctuation, is really not; it's a rhetorical indicator. So is the interrogation sign (?). I think that the use of "hey" as in the sentence above is sort of a signal that what follows is sort of a leading verbal exclamation point, as it were.

Dave Oesterreich