(Note: Title is not a sexual innuendo.)

When Twilight heads out to run a few errands, she is stopped by somepony with a very peculiar question: can I sit on your face? Appalled, she obviously declines and goes on about her day. But then more ponies ask. The question is "spreading" fast, and when one of her friends joins in on the odd requests, she determines that something is very wrong.

Twilight must race against time and pony butts to find out where this "disease", this "joke", is coming from, and how to stop it before all of Equestria wants to "sit on your face."

Rated Teen because butts.

(Once again, the title is not a sex pun.)