1. A huge smile that shit eaters can't stand(aka people who take themselves too seriously) When a serious butthurt occurs followed by a SEG said "victim" often flees to Urban Dictionary to bitch and moan about SEG's or someone wearing one. These whiners are often on the wrong end of the stick(no pun intended) and are too dull to grasp that their bitching only intensifies the "shittiness" of the grin. Naturally humiliation of the "victim" is in direct correlation to the "shittiness" of the grin.
In any situation it's best to be the person wearing a shit eating grin as opposed to the person who just ate shit. The person wearing the shit eating grin possesses both self-control and inner contentment concerning present circumstances. (possibly but not always at someone's expense) .
Many women love a shit eating grin, as it expresses the mystery of inner laughter as well as a completely unabashed authenticity regarding another person. All without blabbing on about some bullshit she probably doesn't care about.
A shit eating grin is one of the most powerful/sexy smiles in the world when expressed correctly.
Shit eating Jim and Butthurt Tom are walking on the sidewalk when Tom slips on a banana peal and falls on his ass. Jim flashes an enormous shit eating grin.
T: Wipe that shit eating grin off your face!
J: What grin?(while still smiling)
J: (normal face) Alright Tom get up let's go.
T: No!!!! I'm going to go home and write an article about how butthurt your smile makes me feel!!!
J: (grins) o.k. Tom you do that.