breakfist
A knuckle sandwich.
Biff Tannen stated that he owed Marty --- or to his knowledge, "Calvin Klein" --- a vengeance-punch for "causing 300 bucks' worth of damage" to his car. Said pummeling did not end up benefiting Biff overly, though... perhaps said deliquent teenage hothead should have taken a lesson from his great-grandfather Buford, whose own tremendous clenched-hand swing at Marty (or in his case, that irritating dude known as "Clint Eastwood") merely resulted is his almost having an early "breakfist" --- as in, he learned the "hard" way what it felt like trying to bash his way through an old-school bullet-proof vest (i.e., 30 pounds of Good American Steel boiler-plate), and it nearly fractured his knuckles!
