I just locked myself out of my house

Dark One said:
How the hell does that work anyway? I thought it was only in the movies.

I'd tell you, but I'd have to kill you.

It only works with sliding bolt locks (for lack of a clue on what they're really called). Slide the card back-n-forth until you can "dig" it between the bolt and the inside of the door jam. Turn handle. Break in.