In chapter LXII of the second part of Don Quijote by Cervantes, ("Which deals with the adventure of the enchanted head, together with other trivial matters which cannot be left untold"), the Don and Sancho are invited by their host to see a magical talking head made of bronze, which, their host claimed, would truthfully answer any question put to it.
Quijote, Sancho, and the other guests all ask the head various questions, which are answered in rather banal and trite ways. Sancho, for example, asks "When will I escape from being a squire?", and the head replies "When you stop serving." In the Spanish original, Sancho then observes "no dijera más el profeta Perogrullo.", which Ormsby translates faithfully, if unimaginatively, as "“the prophet Perogrullo could have said no more.”
"Perogrullo" is a traditional comic character from Spanish literature, who is famous for making obvious remarks, like "The sun sets at sunset". Since Ormsby simply translated Sancho's statement without providing any explanation, I wondered if more modern translations gave some more context. Rutherford instead translates it as:
The great prophet Stan Streeson couldn't have done any better!
This avoids the problem of explaining who Perogrullo was, but introduces a new question. Who is "Stan Streeson"?