He is so old that his blood type was discontinued.

This is a hyperbolic one-liner built on an anachronism: blood “types” are a modern medical classification, so claiming someone’s type has been “discontinued” comically treats biology like an obsolete product line. The joke intensifies the familiar “so old that…” roast format by borrowing the language of consumer goods and institutional policy (things get phased out, discontinued, replaced). It implies extreme age while also poking fun at society’s tendency to categorize people and treat even intimate human facts as bureaucratic labels. In performance, it functions as a quick, punchy insult that relies on surprise and the absurdity of medical taxonomy being subject to fashion.