Green’s Dictionary of Slang

no shit, Sherlock! excl.

also NS²! n.s.s.!
[Sherlock is a pun on holmes n., which itself puns on homes n. + ironic use of the fictional detective Sherlock Holmes]

(orig. US) ext. of no shit! excl.

[US]C. Durden No Bugles, No Drums 222: No shit, Sherlock. What gave you the first clue?
[US]Eble Campus Sl. Spring 5: NS2 – N-S-squared. A retort to a stupid question.
[US]P. Munro Sl. U. 138: Did you know that the Rose Bowl is in Pasadena? — No shit, Sherlock!
[US]Eble Sl. and Sociability 37: Acronyms in which the letters are pronounced together as a word are much less frequent: [...] No shit, Sherlock ‘too bad’ is cleverly NS², pronounced N-S-Squared.
[UK]L. Gould Shagadelically Speaking 122: Austin shouts ‘Vanessa, you’re a Fembot!’ in disbelief, she comes back at him with, ‘No shit, Sherlock’.
[UK]J. Joso Soothing Music for Stray Cats 84: ‘No shit, Sherlock.’ Nothing gets past these guys does it, eh?
[Ire]L. McInerney Glorious Heresies 194: My dad’s grand, my brothers and sisters are grand and she’s sure they all miss me. No shit Sherlock, thanks for the update.
[US](con. 1962) J. Ellroy Enchanters 278: ‘[T]he Sex Creep’s creepiness moves us ever closer to Marilyn Monroe.’ No shit, Sherlock.