「大丈夫です」 means "no thanks"? Yes/no traps at the register
You ask "Do you need a bag?" and the customer says 大丈夫です, "I'm fine". Do they want the bag or not? This is the classic trap. Here is how to tell yes from no.
大丈夫です = "No, thanks"
大丈夫 means "all right" or "OK". As an answer to an offer, 大丈夫です means "I'm fine without it", so it is a polite no. Japanese dictionaries now list this refusal meaning too (the 明鏡国語辞典, 2nd edition, notes it as a newer, casual use spread by younger speakers).
| You (part-timer) 袋はご利用ですか？Fukuro wa go-riyō desu ka?Would you like a bag? | |
| Customer 大丈夫です。Daijōbu desu.No thanks. (→ no bag) | |
| Customer いいえ、大丈夫です。Iie, daijōbu desu.No, thanks. (いいえ makes it clear) |
Other ways to say no
| Customer いらないです。Iranai desu.I don't need it. (Clear no.) | |
| Customer あ、いいです。A, ii desu.Oh, no thanks. Careful: いい means "good", but here it is a no. | |
| Customer 結構です。Kekkō desu.No, thank you. (Polite, a little formal.) | |
| Customer そのままで。Sono mama de.Leave it as it is: no bag, no heating. |
いいです can mean both "that's fine (yes)" and "I'm fine (no)". At the register, a short いいです to an offer, often with a small wave of the hand, almost always means no.
Ways to say yes
| Customer お願いします。Onegai shimasu.Yes, please. | |
| Customer はい、お願いします。Hai, onegai shimasu.Yes, please. | |
| Customer Mでいいです。Emu de ii desu.A medium is fine. (〜でいいです with a choice = yes, that one.) |
The quick rule
- Hear お願いします / ください / 〜で → yes.
- Hear 大丈夫 / いい（です）/ いらない / 結構 / そのまま on its own → no.
And when you are the customer: 大丈夫です with a small shake of the hand is the most natural way to say "no thanks" at a konbini.