Alice,
i know exactly what you are taking about. and i just get irritated by such people. We had few friends come over few weeks back and around the same time, the famous british lady(susan boyle) who sang on their version of 'american idol' was in news.
I am sure everybody in our group had heard the news but when this particular guy started talking, he got it all wrong! incorrect age, incorrect name...incorrect facts(she is handicapped or something on those lines). when i tried to correct him, he was quite adamant that he had the correct info. i didn't push much, since they were our guests. I just gotup and went into kitchen to have a big glass of water to calm myself down

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but i know what you are saying
