Are you from the future? Then you're cordially invited to Pinkie's Time Traveller Party! Come as you are. No need to RSVP.
In 100 years, somepony in Ponyville will unearth a time capsule, and inside they'll find Pinkie's open invitation to her new friends whom she hasn't met yet because they're all in the future. Will any guests of honor show up to the party at the appointed hour? Pinkie's counting on it.
Inspired by an "experiment" by Stephen Hawking.