Literal translation
to make a shitload, a blunder
Meaning
to make a blunder
Explanation
Cagado comes from the verb caga, to shit, to fail, to collapse, or to back off, a coarse verb with a literal scatological sense that developed a whole range of figurative meanings tied to failure and clumsiness; faire uno cagado literally means making a shitload, and is used figuratively to mean making a blunder, committing a clumsy or regrettable mistake. The image stays true to the bodily, coarse register of the starting verb, the unfortunate outcome of an action being compared to excrement, a common deprecating image across many languages for failure or a blunder. The expression is very common and familiar, used in almost any situation where someone admits to or is blamed for a mistake, without the word keeping in this use as crude a connotation as its original sense. The shift from a scatological meaning to that of a blunder is a classic mechanism of popular speech, where the body supplies the vocabulary of failure.