Happened to me a couple of years ago at Walsall. I was seated in seat 9 and was chatting to the guy in seat 10. I saw a guy in seat 4 call the BB bet but he was one of these people who announces raise, but actually puts the call in physically and then follows with the raise.
I only saw the call placed in and when I announced "Call" (with my 6-9 spades), I was made to match his full raise, leaving me seriously short-stacked. As it was, 2 spades flopped and I shoved and busted his aces !!
What annoys me is that on MANY occasions since, I have seen this happen and on EVERY occasion, they have been allowed to take the chips back.
I wish poker had standard rules........