Americans are generally ignorant about their "native" language. Our schools lack discipline and rigor (or rigour) and so entire generations of students don't even know the simplest grammar rules, like those dealing with pronouns.

For some reason, people can't decline two pronouns at the same time if one is "I" (or decline "I" when used together with a noun). The typical grammatical error of the past generation, along the lines of "Me and you went to the store", was corrected by teachers quite frequently: "No, say 'You and I went to the store.'"

However, the teachers were just too lazy, stupid or indifferent to continue the explanation of just WHY the previous example should be "Sally and I" instead of "Me and Sally". The conclusion many have come to (apparently), is that the proper form is "I" whenever there are two pronouns or "I" is used with a noun. This has led to some completely incorrect sentences, such as:

"For you and I, this is important."
"I don't know what they are going to do about you and I."
"He saw you and I, didn't he?"

Interestingly enough, the problem seems to be with "I", and only with "I". For some reason, people don't get the simple principle that "I" only appears as "I" when used as the subject of a sentence. As a direct object, indirect object or object of a preposition, it's always "me". I suspect that most of the people who make the mistake would not make it if the first person singular pronoun appeared by itself. I haven't heard, even once, sentences like:

"For I, this is important."
"I don't know what they are going to do about I."
"He saw I, didn't he?"

This error irritates me more than saying "hold down the fort".