That's right--I got 'em all. I have no proof so you'll just have to trust me on this one.
5:1, 5:2 - Princess Celestia accidentally transforms Diamond Tiara into an alicorn princess. Chaos ensues.
5:3 - Flash Sentry from the Equestria Girls universe visits Ponyville. The Mane 6 spend the whole episode talking about how hot he is.
5:4 - Cheerilee goes back to school--in Prance. Sacre bleu!
5:5 - A spell gone awry causes Celestia and Luna to switch bodies with Snips and Snails. Unfortunately, it's permanent.
5:6 - The Apple Family stands in front of their fence drinking cider and saying "yup."
5:7 - Rarity saves Spike's life. The Dragon Code demands that he stay by her side and repay the debt. Little does he know what his pony mistress has in store for him. (Working title: "Fifty Shades of Off-White.")
5:8 - The Changelings take over the Crystal Empire, then give it back because it was just way too easy. (Crystal Heart powered by love + changelings = very bad news.)
5:9 - The background pony episode. Unfortunately, it is based on MTV's Real World where they all must live in an apartment together.
5:10 - In a stunning development, Rarity, Sweetie Belle, and Ditzy Doo are able to visit the real human world. They spend the whole time in a shopping mall where Rarity just can't find the right color lipstick.
5:11 - Somepony gives Pinkie Pie some mare-a-juana cookies.
5:12 - Apple Bloom and Sweetie Belle accept Scootaloo's invitation to a "house party," not realizing her house is a cardboard box in the woods.
5:13 - Princess Luna (still in Snips' body) learns that she owes over 1000 years worth of back taxes from when she was imprisoned on the moon. The entire monarchy goes bankrupt, leaving Mrs. Harshwhinny the new ruler of Equestria.
5:14 - Twilight Sparkle becomes a fan of the Twilight series. Kristen Stewart and Robert Pattinson guest-star.
5:15 - Discord pursues his lifelong dream of being a country singer.
5:16 - Rainbow Dash goes so fast that she accelerates her own evolution and starts turning into a lizard.
5:17 - Silver Spoon reads Nietzsche and concludes that Celestia is dead.
5:18 - King Sombra comes back from the dead to challenge Tirek to a grunting and growling contest.
5:19 - Owloysius visits the Mirror Pool, makes a million copies of himself, and attempts to take over Equestria.
5:20 - Pinkie Pie gets diabetes.
5:21 - Ponyville catches disco fever. 99% of the episode is singing and dancing. Donna Summer guest-stars.
5:22 - Fluttershy wants Celestia to change her into a tree.
5:23 - The CMC messes around with love potions again, causing every Mane 6 pony to fall in love with all the others.
5:24 - With water skiing becoming an increasingly popular sport in Equestria, Rainbow Dash is determined to successfully jump over a shark. Granny Smith raps at the end.
5:25, 5:26 - The finale. A supposed flashback to the ending of 'Over a Barrel' reveals that Pinkie Pie and Rarity are still stranded in the desert, and everything that has happened in the series since then was just stories they were making up to entertain each other.
(24 bad ideas. I feel strangely proud.)