Americans never seem to get this right. They always say "you and I", "Lucy and I", when, 9 times out of 10, it should be "you and me" or "Lucy and me". I think that this all went wrong because most people seem to say, naturally, " Lucy and me are going out tonight". As Grunty said in his or her second response, it is so common as to be almost acceptable. It is like when someone asks, "Who is it?" and you reply, "It's me." It would sound crazy to say "It is I" or, even worse, "It's I". There is no problem in Italian, for instance, where one would say "Sono io" (it is I, or Am I to be really precise ).
So, when people are corrected and told that "Lucy and me" is incorrect, and that they should say "Lucy and I are going out tonight", they think that "Lucy and I" is always correct, so you hear the abominable "between Lucy and I", and "Good night from Lucy and I", etc.