One who behaves in an angry, annoying, rude, mean, or no-fun attitude, while simultaneously screwing you over in any way.
(Being a dick) + (Shafting someone) = Dickey Shafter
Jack - "Yesterday Marcus made me late for our double date because he took 45 minutes to shower. Once he got in the car, he kept telling me that he is going to hate the movie that we're going to see, and he was spitting insults left and right!"
Roy - "Yeah, Marcus has been such a Dickey Shafter lately"
Someone who often throws another under the bus for their own benefit. Often, this culprit makes up excuses as to why he or she screwed over the other person. This person is also a large, veiny dick.
*After an hour or two of waiting, Noah comes to the conclusion that Martin isn't coming to get Noah to drive him to the party*
*Noah decides to call Martin up*
Noah: Why didn't you get me Martin?
Morgan: Umm, I was flossing...
Noah: Yeah okay you have dentures!
Morgan: Oh... well I was taking a dump...
Noah: You're such a Dickey Shafter!