Garbage in, garbage out | GIGO

Meaning: Incorrect or bad input results in incorrect or bad output.

Note: garbage (noun): rubbish, trash, nonsense

Origin: This saying originated in computing, where faulty data going into a computer inevitably results in faulty results coming out. This is the origin of the acronym GIGO.

Variety: This is typically used in American English but may be used in other varieties of English too.