- Granny Smith trying to set up Rainbow Dash and Big Macintosh.
- The nickname 'Twilight Snarkle'. Even Twilight admits it's funny.
- The context in which it's used; Rainbow Dash and Twilight are having a mutual "apology" fest with each other, only for Dash to randomly apologize for calling Twilight that name. Twilight is about to respond (presumably with forgiveness) only to point out that Dash never actually called her that in the first place.
Funny / Friendship is Empathy