木村：あっ、島田さん、おはよう。
佐藤：あのう、結婚して名前が佐藤になりました。
木村：すみません。ついうっかりして、旧姓を呼んでしまって。
Ukkari suru
Kimura: A ', Shimada-san, ohayoo.
Satoo: Ano, kekkon shite namae ga Satoo ni narimashita.
Kimura: Sumimasen. Tsui ukkari shite, kyuusei wo yonde shimatte.
Kimura: Oh, Ms. Shimada, good morning.
Sato: Actually, I changed my name to Sato when I got married.
Kimura: Oh, sorry. I wasn't thinking; your maiden name just slipped out.
Ukkari suru is used when you make a mistake through being careless, not paying attention, or not concentrating.
Everyone has occasions when they Ukkari shite machigaeru (Make mistakes through carelessness), or Ukkari shite wasureru. (Overlook something because you're not concentrating. )
We have all experienced occasions when we mistakenly call someone by their maiden name, as in the conversation above, or Ukkari inemuri shite ite, densha wo nori-koshite shimau. (Accidentally doze off and miss our stop on the train.) However, it's not so often you hear of people who Ukkari shite inochi wo otosu (Lose their lives through a moment of carelessness.)
During the Meiji period, before the Russo-Japanese War of 1904-1905, a man named Shozo Yokogawa, by order of the emperor, was sent to China as a spy.
He spoke fluent Chinese, and because Ukkari nihongo wo hanasanai yoo ni, itsumo ki wo tsukete ita (He was always careful not to inadvertently speak Japanese) , managed to carry on his life as a spy without coming under suspicion. One day, however, he was arrested as a spy.
The story is that, Ukkari shite, kao wo aratte iru tokoro wo mirarete shimatta. (Someone saw him while he was absent-mindedly washing his face.)
You may wonder how they were able to tell that he was a spy simply by the way he washed his face. The answer is, when the Japanese wash their face they rub their hands in an up and down motion, whereas Chinese move their hands from side to side.
I do not know whether this is true or not, but it is a good story, I think.
No matter how good at the language he was, his gestures and facial expressions were enough to give him away.
When I am teaching Japanese to foreign students, I make a point of teaching them not to bow or nod their head at the same time as teaching them to say arigato. It is only when gestures are naturally associated with words such as this that I think you can say that you have really learned the words.