At one point or another in elementary school the and I rule is drilled into students' minds. Perhaps curriculum is reacting to some previous incorrect overuse of and me in certain situations. Well, now the reverse seems to have seriously taken hold. Late gen Xers and millenials alike are using and I in any and all situations. It's as though there aren't any other options. Oooh, but there is. And grown people getting this wrong really grinds my gears.
How do you know what to use? In which situations is I the correct choice, and in which other situations should me be chosen? It really isn't difficult to figure out. I honestly believe no one over the age of 15 should be getting this wrong.
Let's start with the one everyone actually seems to get right.
We are cooking dinner.
Me am cooking dinner. (This clearly makes no sense.)
I am cooking dinner.
Ding ding ding ding ding! Now just add the other person back in, tack on the plural pronoun conjugation of the verb, and that's it!
So in this case:
We are cooking dinner. --> John and I are cooking dinner.
A good rule of thumb:
We always expands to be noun/pronoun + I.
Now let's tackle the one which actually seems to baffle the minds of otherwise intelligent people.
The incorrect tendency of so many nowadays is the following:
The drink spilled all over us. --> The drink spilled all over John and I.
No joke . . . hearing this actually makes me want to pull my hair out. This is wrong. Sooooo wrong! Employing the same method used above, let's eliminate the other person.
The drink spilled all over I. (Again, this does not make any sense.)
The drink spilled all over me.
As such ...
The drink spilled all over us. --> The drink spilled all over John and me.
Rule of thumb in this case:
Us always expands to be noun/pronoun + me.
Yes, and me does exist. And yes, you should use it.
If all else fails, think of the nursery rhyme that goes like this:
Patty cake, patty cake, baker's man;
Bake me a cake as fast as you can;
Roll it, pat it, mark it with a B;
Put it in the oven for baby and me.
If you think the final phrase is grammatically incorrect, you have poor grammar.
For a more technical explanation, go here.
"Lighten up, G. It's the internet. Who cares?" A couple other interesting reads: