One who will do anything to further his own personal interests without regard for the impact his actions will have on the interests of his "friends" or colleagues. Buddyfuckers cannot be trusted to "do the right thing" and have no regard for abstract principles such as ethics or morals.
This title is used frequently in the U.S. Naval Aviation community. When speaking discreetly, Aviators may say "buddy is only half of a word."

One who has a mania for music.

In military lingo, also a "Bravo Foxtrot."

noun: Someone who tends to give their friends the shit-end-of-the-stick, someone who screws their buddy for selfish reasons.

Anyone who ditches or lets their friend down, usually to do some generally undesirable task, especially if it is taking blame, exhausting work, getting in a fight. A buddy fucker usually takes a lot of blame from his friends, and depending on how bad the ditching was, may not be friends with the fucked buddy much longer.

One who screws a friend for his own selfish gain.

Also known as Blue Falcon in military slang.