During a crossover with Royal Sketchbook, Luna gets drunk and mistakes Sci-Twi for Princess Twi and nibbles her back. Sunset, also drunk, makes out with Princess Twilight in retaliation. The last part shows both Twilights holding their spouses back using magic with faces that scream "I'm so done with this bullshit."Here's the whole thing in its glory.
A New Year
The Plan
Pinkie wearing a frog costume when spying on Sci-Twi and Sunset with the rest of the Mane 6 during The Plan.