shit-eating grin
A broad smile indicating a joyous secret.
<Insert photo of Dennis Quaid.>
Does anyone know the origins of this marvelously descriptive phrase?
It would seem more natural to say “shit-eating grimace”, but perhaps the real secret is anything disgusting done secretly is enjoyable?
Discuss.
I’m not sure, but I’d look for a military origin. It sounds like something a D.I. would say.
I had always imagined it was related to expression, “Happy as a pig in shit.”
I have no cite, but I was always led to believe that it was the sort of grin where you’re smiling so wide that your lips don’t touch your teeth at all – the same as you would be inclined to do if your teeth were covered in shit.
as long as we’re all guessing, I’ll add my own theory:
I always thought that a shit-eating grin differs from a regular grin because it is bigger , and obviously fake–i.e. not a natural reaction.
You grin and smile naturally at a funny joke. You grin and smile non-naturally when you have something to hide. The more embarrassing your secret, the wider your grin. (Think of a young child, caught red-handed with a pilfered cookie)
And there ain’t many secrets more embarrassing than having to hide the fact that you just ate shit. .
Ergo–a shit eating grin.
I rest my case.
Carry on.
Always wondered what that meant. Your explanation makes a lot of sense mrklutz.
I apologise in advance for a post that might offend Asians, but I have always heard this phrase in a military context, especially in reference to Asians. It is because some Japanese, Korean or Vietnamese people (depending on the war) would appear to grin at inappropriate times, such as when undergoing some form of verbal, mental, or physical abuse.
Whaaa…
You guys are way off…
Imagine you have a secret shit eating habit. You sneak off to the men’s room at work and munch on a juicy one. All of a sudden, the boss and a client walk in and catch you in the act. Busted, no denying it.
All you can do is grin like an idiot…a shit eating grin.
I’m also just guessing, but I thought that a shit-eating grin is what someone does when they’re sucking up to another person in order to get something from them. That is, they’re matphorically taking their shit, so they have to put on a fake, self-deprecating expression; a shit-eating grin. Like thus: 
metaphorically. :smack:
Carry on!
Imagine a situation where you are gloating big time. You’ve got this big, dumb smile on and you’re thinking to yourself (about the person you’re gloating at) “This bastard can just eat my shit.”
Voila! Shit eating grin.
It’s been asked before, but we came up with a complete blank.
Nunavut
That’s an interesting derivation. (I never heard of any of these by the way).
Also, I always thought the definition of such a grin was exactly as you describe it - smug, self-satisfied, “I’m better than you are” attitude.
I always thought that it was directly connected to the expression “He’s grinning like a opossum eating shit.” 
Yes. Well, of course I agree!
That’s the way I’ve always understood it as well.
While I can’t explain the popularity of the specific phrase (vs. other types of grin) , adding a touch of meaningless vulgarity often adds public appeal to a phrase. You can coin any number of logical and apt alliteration on a Holmesian theme, but none will have the staying power of “No shit, Sherlock”
For that matter, the expression “No shit” itself is a semantically void replacement for the onomatopoeic "Duh!’ and “Doy!”. It has no obvious connection to
“Shit” used to be a much stronger word, which may help explain its initial popularity. Which do you think would be more evocative and memorable: “a leg-humping grin” or a “sheep-f***ing grin”?
I suppose my point -which applies to many colloquialism threads- is that phrases often gain popularity for reasons aside from their meaning. While we might have briefly asked ourselves "What shit?, we understood the meaning from context --and so did everyone else. Trying to construct an etymology is pointless because there may never have been one. No one will turn up a missing manuscript for Doyle’s “The Case of the Coprological Feast” – and even if they do, the fact that it was previously unknown effectively rules it out as the genuine origin of the public phrase.
Even if there was a published origin, I’d argue that the correct answer to “why do we say X” is “because it’s catchy” – not “because it appeared in a twelfth century treatise on natural history”. When it comes to common phrases, the “popularity” is key (who cares about a phrase like “sheep sneakers” that may just as valid, but limited to a single person?), and meaning is secondary. Catchiness is the one true “reason”, not some etymology that is unknown to almost all users anyway.
I dunno. I agree that many people can use such colorful colloquialisms with complete ignorance of their origins and intended meaning circa their invention; but I think the deeper etymological questions are still valid enough. Somebody first spake the words “shit-eating grin”, and likely had a vivid intention and meaning they wished to convey. It may be a worn-down version of a much more explicit phrase (e.g. the opossum etymology above). “Catchy” explains pereptuation, but I think these phrases have more to them than random juxtaposition of vulgarities for the sole purpose of visceral impact.
Excellent parody of my pompous posting style, Loopydude! Truly the soul of understated wit (and your factual argument is well taken, BTW).
I don’t know why I often post that way here (Only three sites bring that out in me. The other two are decidedly casual, but since I’m an old-timer there, and quick with a pun or dirty joke, they put up with me)
Wow. Er, actually no parody was intended; rather I was trying to rise to your level. I post with a lot of crass and imprecise language here, and forcing myself to occasionally use my brain when I write is good mental excercise, IMO. Not to gush, but I admire people who can write, and would do better to emulate them more often.