Unaware Dick Talker (UDT) refers to a person who comes across as a jerk when talking but does not realize and is not trying to be mean.
For example, they'll be giving advice while you two are playing a sport, but the way they phrase what they say and the tone of their voice makes you feel like shit even though they mean well.
Another example is when you make a comment in class and then they follow-up on your comment by saying they fundamentally disagree with you. Instead of respectfully disagreeing, their phrasing and tone makes then come off as a total and utter dick.
They are usually condescending and think they know everything and their opinion is superior; however, they are unaware that they come across as a dick and should not be confused with actual dicks.
John is such an unaware dick talker. I'm scared to give my presentation tomorrow because I know he will talk about how he disagrees with me in a very mean manor.