[prez2032]

Well I know this is legal for a fact at the Excalibur. (At least, it was in January.) My friend was playing the baby NL game there and when an old rock made a hugely oversized raise into a ragged flop and a smallish pot, my friend flashed him pocket Kings and the guy's breathing went through the roof, like someone who isn't getting enough oxygen all of a sudden. My friend called, and built up a nice stack. I believe you need to be heads up for this to be legal, and I certainly don't think it would be always be wise or useful to try doing it, but it's interesting to know that it is an option.