Can be typed as well.
Bob: "Joe, watch out for that large pothole you seem to be unknowingly driving into."
Joe: (avoiding pothole) “Thank you for your timely and straight-forward warning. I appreciate you using the first sentence after you were alerted to this danger to tell me about this pothole, instead of uttering a one-worded, useless phrase.”
Modern protocol, same situation--
Bob: (sarcastically) "Um..." Joe: “What?..... What?” (car drives into pothole)
Bob: “Wow, good job.”
usually it means that the speaker is searching for an idea (or at least thats usually when i use it)
dean kamen: um...that is...um well...
Person 2: Um, Vader never said that line.