jissom:

Widespread US and UK slang term for semen . An unstable, polymorphous word with many orthographic variations: chism ; gism ; gissom ; gisum ; gizzum ; jessom ; jism ; jiz ; jizz ; jizzom ; jizzum . It's usage, common a generation ago, is fading, being replaced with come or cum . See semen for synonyms.

ETYMOLOGY: Believed by some to derive from the Latin jacere , meaning throw ; others see a distortion of jetsom, ballast thrown overboard from a ship.