Here's why:
* Pronoun Case: "Me" is in the objective case. It's used when the pronoun is the object of a verb or preposition. You would use "me" if someone was doing something *to* you.
* Subject Pronoun: You need the subject pronoun "I" to be the subject of the sentence.
Correct Ways to Say It:
* "Ericka, Ethan, and I..." (This puts the other names first as a courtesy, but you can also say "I, Ericka, and Ethan...")
* "Ethan and I..." (If the context is clear who Ericka is)
Example:
Incorrect: Me, Ericka, and Ethan went to the park.
Correct: Ericka, Ethan, and I went to the park.