Knackwurst is a cooked
and subsequently smoked German sausage
Knackwurst is commonly cooked on the grill like the commonest sausage varieties, but due to it's girth (it's at least twice as thick as common grilling sausages) it remains juicy and moist even when the casing is crisp and dark brown.
Knackwurst's constituent meats are usually pork and beef, with a hardcore dosage of garlic in the seasoning mix.
Knackwurst is also known in the USA as Knoblouch or Garlic Sausage.
The etymology of the sausage's name is said to derive from the old German knacken, meaning "to crack" (the loud report they make when cooked, presumably).
research sources include bartleby.com and the National Hot Dog and Sausage Council