So... We have all heard about Lauren Faust's tweet about ponies using toilets, or, to be precise, not using them: http://www.equestriadaily.com/2013/01/breaking-news-equestrian-outhouses-are.html
But AJ and Pinkie used a toilet in the Last Roundup.
And I've just found that comic: http://pony-berserker.deviantart.com/art/Do-Ponies-Use-Toilets-355964953
In addition to this hilarious fan-fic http://www.fimfiction.net/story/75393/princesses-dont-potty
And this strip from a webcomic http://www.collectedcurios.com/sequentialart.php?s=751
It's something we don't think and don't want to think, but...
What's your headcanon about this?
(I personally like the explanation from this comic: http://pony-berserker.deviantart.com/art/Do-Ponies-Use-Toilets-355964953 )