he he. Have any of you got kids?
Any enterprising child, especially a boy, will be able to lever up the earth cover in a couple of seconds with a wide variety of implements freely available around the house.
Get some plug covers as suggested above, they'll only slow the kids down but it'll give you the time needed to wrench them away when you find them with some stripped down earphones in their mouth with one lead in the neg and one in the pos.
My lad once used some car keys to lever up the cover in the five seconds my wife was trying to stop the video recorder from eating the jam buttie he'd placed in there, had a pencil in the pos hole and was looking round for something equally condutcive to ram in the other before she returned from the said sandwich protection mission.