ROFL Beethoven, and tell Tchaikovsky the news

[Black Aeronaut]

Sorry, it's pony stuff, but it's still freaking hilarious.
Foreground info: Twilight Sparkle has created a device that borrows Luna's and Celestia's powers to do their job for them... and Celestia has her first morning off ever.

Many times over the years, Celestia had
half-lamented, half-jested that since bonding with the sun she had
forgotten entirely what it felt like to sleep in late. (waking up,
raising the sun and then dragging herself back to bed didn't count, in
her mind. She never quite got back to sleep.) Now, with Twilight
Sparkles' wonderful Clock (1)tending to the rising and setting of the
Sun, for the first time the Sun Princess could indulge in that
mysterious pastime. Luna found her stone dead asleep on her bed, lying
on her back, hooves curled up, sunbeams dappling her belly as she slept.
She had an absolutely blissful expression on her face. Every now and
then a gentle snore rose from the royal snout.
Luna
stifled a giggle. Then she recalled how their mother had woken them
when they were foals and had been naughty enough to sleep in late. An
evil grin slowly spread across her face. She carefully tip-hoofed over
to the bed. She leaned over Celestia's bare tummy, took in a huge,
gleeful breath---
Celestia's eyes snapped open. "Don't you dare," she said.
Too late, she was committed! Luna lunged.
BRAAAAAAAAAAPPPPPPPP!!!!!!
"Yaaaaagggggh!"
All four snowy hooves shot into the air as Luna proceeded to give her sister the Almighty Royal Belly Zerbert of her life.
The
next moment Luna could be seen fleeing Celestia's chambers, shrieking
and giggling like a loon, with Celestia in hot pursuit.

Best part of all?  I now know what to call it!  Belly Zerbert!  Hilarious!