This is only partially related, but the posts on whether or not you can get a hiney hickey reminded me of it. On a WN flight, I was going to use the restroom shortly after boarding (plane was still on the ground). The FA said there was something wrong with it and it would only function once we were aloft. Seemed weird to me, but okay, I can wait. Then they made an announcement that the restrooms would only be open once we had reached a certain altitude/cruising speed...they said why, but I don't remember. They did, indeed, work once we were aloft. I've never run into this again...wish I could remember the specifics as I'd love to see if anyone else has ever run into this.