Having one pet rock is cute; it means you’re a sensitive guy, and showing it to someone shows trust in a relationship. Having forty pet rocks is creepy, and should not be shown to your marefriend on a first date.
Angel Bunny is feeling poorly and nopony knows why! Being the good friend that Rarity is, she readily volunteers to help Fluttershy get to the bottom of things!
The CMC is bored out of their minds with nothing to do on a lazy summer afternoon, so they decide to drop in on a friend to see if there's anything fun to do there.
Derpy and the Doctor. They were once so much, but now Derpy is old and dying. And she wants to go on one last adventure before she has to go. Even if she doesn't want to go.