I actually wanted to draw a comic about something like that... but never did.
It starts with Sweetie waking up in the morning. She goes down the stairs and finds Rarity in the kitchen making the breakfast. Rarity asks Sweetie if she can fetch the post, so she goes to the door, and Wawity says something like "Sweetie, dear, you do remember what day it is, don't you?" and Sweetie is like: "Yeah, it is Friday, isn't it?".
Before Rares has the time to answer, Sweetie opens the door and gets buried by a giant avalance of letters, she digs herself out of it and remembers: "Oh yeah... It is Heart and Hooves day."
Then the pont of view changes so that you can see the botique from outside, and there is a giat heap of letters, with hearts and tiny Rarity pictures on them, blocking the door, but one can also see Spike. Who has a kinda grumpy expression and a tiny shovel, and with this shovel he scoops letters on a tiny campfire to burn them all... END
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Hey i just said i wanted to draw it some time ago... Not that it would be funny. Im german, im incapable of being funny...