I don't know about you, but when I was a kid, the following conversation took place almost every day at home and at school:
Kid: "Mom, can Jerry and me go to the park?"
Mom: "Jerry and I, darling."
Kid: "Me and Susan want to sit together."
Teacher: "Susan and I, and no, you'll just chat the whole time and not get any work done."
Er, maybe that last part was just directed at me. Nothing to see here, folks. *ahem*
Basically, this auto-correction from our elders beat into our collective heads that "person X and me" should always be replaced with "person X and I." But for some reason, they always neglected to tell us why it had to be that way---which is unfortunate because it's led to a lot of misunderstandings.
I find that I have greater success as a copy editor if I know why a certain rule is enforced. It's easier to remember the difference between "convince" and "persuade," for example, if I know that action is only associated with "persuade." (You persuade someone to take action, but you convince someone of a certain belief. I'm getting off topic, though...more on that in a later blog post.)
Unfortunately, with the "I" vs. "me" debacle, a lot of people don't understand the reasoning behind it, so they take the constant correcting to heart and just sub out "I" for "me" whenever they're talking about things done with another person.
Which is why you'll occasionally see an otherwise extremely intelligent person use incorrect sentence construction:
"He brought the ham for Mark and I."
In this case, "Mark and me" is grammatically correct, and "Mark and I" is very wrong. If you're the object of the sentence---the person affected by the action in the verb---then you would say "me."
"Will you come to the fair with me and Josh?" Yep, that's correct, too.
"Kerry really likes you and me." Also correct. (Of course, you could nix the awkward construction there by simply changing it to "Kerry really likes us.")
Isn't it funny how sometimes we try to be overly correct and end up misusing words anyway? Between you and me, sometimes the easiest phrase is the right one.