This was a little tough but the choice seemed kinda obvious to me. I decided to go with the moment Kurt came out to Mercedes aka the first time he told someone that he was gay. So Mercedes had developed a crush on Kurt, and to avoid telling her that he was gay, he made up a lying saying that he had had a crush on Rachel. (Then Merci busted the window of his car, oh yas) But then she calmed down and what happens from then on is in this video:
I thought it was very cute and her reaction to it was the best possible. Also, it was the first step for Kurt.
Day 09- Your favorite Kurt/Mercedes moment