grammaticality - Should I put myself last? "me and my friends" vs. "my friends and me" or "my friends and I"

I've always been taught to put myself last when referring to myself in the same sentence as others but the usage of "me and..." seems to be everywhere these days. The misuse of the word "me" instead of "I" aside, is there some new rule I haven't heard of? Shouldn't we put ourselves last regardless of the "me"/"I" usage?

Examples of "correct" usage:

My friends and I went for some ice
cream. Did you see my friends and me
at the ice cream stand?

Examples of "incorrect" usage:

Me and my friends went for some ice
cream. Did you see me and my friends
at the ice cream stand?

Note: I was also taught that the only person who could put themselves first was the queen.

Answer

The difference between "I and my friends" and "my friends and I" is purely a matter of courtesy - they are both grammatically correct. I would tend to stick to the latter though, as it a) is more commonplace, b) is considered more polite, c) seems to flow better.

Indeed, your example of 'incorrect' usage is incorrect solely in that the first sentence uses the accusative (objective) pronoun me, when you actually need the nominative (subjective) pronoun 'I'. The second sentence of that example is correct, since the pronoun needs to be in the accusative, as the object. You seem to understand this though; this is just to clarify.