Having taken a few basic Japanese courses before coming to Japan, I was embarrassed to realize at the end of a couple of rounds at the bar that, while I could capably ask the waitress where she'd bought her socks and how much they'd cost, I had no idea how to ask her for the bill.
Pulling out my pocket dictionary and looking up the expression "I'd like the bill," I found "o-kaikei o kudasai." I said the line, received the check, and reckoned "kaikei" meant "receipt."
I would encounter the word again a few months later at a McDonald's. Having taken my order, the cashier asked me, "O-kaikei wa?" Having no interest in the receipt, I promptly told him I didn't want it. His eyes widened and he cautiously turned to get the manager. Fiddling with the money in my hand and wondering what I did wrong, I slowly realized "kaikei" didn't mean "receipt." It meant "payment," and I had just told the cashier that I didn't want to do it. -- Mike in Shizuoka