Aside from Dark Souls, the only notable Mimics that I remember are from Tales of Symphonia (excellent game, by the way). They were all but immune to physical damage, so if you didn't have a mage, you were screwed. Fun times!
Then, of course, there's Dark Souls. Allow me to briefly summarize my reaction:
"Dum de dum, well this place is certainly cheerful.
Oh, look! Another chest... But it's away from the wall... And slanted...
Alright, just approach it slowly. Wait, there's no way that..."
*Attacks it*
"Jesus Christ, what the- JFDLSKAJKL!"
Apologies for the immaturity, but I feel that it was a fairly common reaction.