In the U.S. Army, someone that does not support the team or unit is said to not support their buddies. Because of this, they are called Buddy Fuckers, because they let down their buddies. Since such things are not considered polite in mixed company, people in the Army endeavored to come up with a similar two letter name to represent the term. Blue Falcon was a cartoon character from the Dynomutt cartoon series during the mid-1970s, a time when many of the people originating the term grew up. So, calling someone a Blue Falcon came to be a substitution to calling them a Buddy Fucker.
