I have two butt plug tails and they both have the same issue, so they make nice ornaments for the dungeon shelves. It's so easy to make a plug that stays in (all they have to do is make the neck small relative to the rest of the plug) but so few manufacturers get it right.

I can assure you that it was not your fault - but the Dommes probably had fun punishing you for it anyway. I am smiling right now and I wasn't even there.