I remember reading an article online about gruesome car accidents and this one poster in the comments section said him and his friend had gotten into a bad accident once (It killed his friend) and his friend was decapitated in it.
He goes on to say that he saw his friends decapitated head just sitting there looking kind of shock with the eyes still looking around as if to say "The fukk?"
The poster said his friends face had a look of shock and fright.
That's something I wouldn't want to remember for the rest of my days.
Now, the poster could've made it up (You know how people do on the internet

) however, after reading up that a decapitated head can stay alive for up to twenty seconds, the guy's story seems pretty legit.