I have! My 'mate' came to the cashpoint with me one time and as she was an old school 'mate' of many years, I wasn't worried about her seeing my PIN.
I then mislaid my credit card and as I am always misplacing things, thought it was around the house somewhere. Two months later, I phoned for a balance and to ask why I hadn't received a statement. My statement address had been changed and my balance had rocketed!
I went to the Police and they discovered that the card had been used a number of times, the first about 10 mins after I had last used my card at the cash point!
To rub salt into my wounds, my 'mate' had been buying loads of drinks in the pub a few weeks before - with MY money and had been constantly asking if I had found my card!
They never proved it was her but I did get my dosh back off my credit card company (who should never have changed the statement address without my authority in the first place).
Btw, she didn't remain a friend for long after that.