This probably doesn't count as an April Fool's from Hasbro, but it's awesome: three new Rainbow Rocks music videos!
"Life's a Runway" -- Rarity
"Friendship Through the Ages" -- Mane Six & Sunset Shimmer
"My Past is Not Today" -- Sunset Shimmer
Both the songs and the videos are legit great. The last song, with Sunset decisively turning her back on her dark past and embracing a new life, is my favorite, but that is no indictment of other two.
In "Friendship Through the Ages", I love how each of the HuMane Six has their own scene with Sunset, with the song subtly shifting to match their personality -- and I love that Rarity's part is straight out of The Yellow Submarine animation!
Finally, the first one -- Rarity's "Life is a Runway" is a great summation of her philosophy of fashion: it's all about making the beauty inside to come outside. And that's what makes her the Best Pony (tm).