Celestia has a ball pit. It's been around for thousands of years, predating the founding of Canterlot. The pit is filled with balls. Celestia shows Twilight just how much fun you can have with balls.

I wrote this because discussion of the idea got majin to ask "what the fuck is wrong with you people"

Kinks include: castrated testicles (no blood), inflation, hyper-inflation, tribbing/scissoring, mentions of bdsm gear, incest by proxy, ahegao, vaginal insertion, Nattō, some mindbreak, kissing, cuddling before marriage.