The term "
wrong idea" is usually said by someone when they don't want you to
contradict something they said. Two things are usually at the center of a wrong idea. If a girl liked someone as a friend but not as anything more then she doesn't want that someone to believe that she likes them
more than a friend. The term is usually said by someone before they reject your thoughts or ideas. The kind of people who say this are more assertive and dominating. They might try to force you into unnecessary submission.