A member of the volunteer public service (EMS, Fire, etc.) who is overly committed to their role, as in one who buys too many emergency lights or owns his/her own personalgear.
"Your car has lights sirens and a boosterline? You are such a buff!"
BUFF originally refers to the B-52 Stratofortress long-range strategic bomber. The enormous aircraft was extensively used for carpet bombing missions in Vietnam and as a first-strike or retaliatory strike nuclear weapon delivery vehicle during the cold war. The crews rarely referred to the aircraft with its real name, instead they used the acronym BUFF, for Big Ugly Fat Fucker.
The fuckers shot down two of our BUFFs last night during a carpet-bombing run. We need better flight planning!
Big Ugly Fat Fuck. The affectionate nickname pilots gave to the Boeing B-52 Stratofortress. Derived from its sheer size (159 feet long, 185 foot wingspan), and the fact that it is ungainly in appearance on the ramp, due to it's 8 engines and bicycle landing gear.
The B-52 "BUFF" is shown many times in the movie Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb, and flew the world's longest combat sortie in 1991 in support of Operation Desert Storm, launching AGM-86 cruise missiles against high priority Iraqi targets.