Identity theft twice, once on my credit card once on my debit card. Credit card guys made it obvious: took their copy of my number to a grocery store and got like $600 in money orders, debit card group was a little more suave: they tacked a $40 charge onto my card with no description except a phone number, and when i called the number, they just claimed they were "accounts handling" and that they couldn't tell me what I had paid for. Looking up the phone number on the internet verified that many others had run into the same thing, where they were just trying to slip a small charge and hope you didn't notice
Monster Hunter: pissing me off since 2010.