my car is a convertible
so saying I locked my keys in it, means I locked them in the boot (trunk for you americans) which can only be opened with a key.
and my wallet is just a small metal thing the right size for cards. so I can't fit a key in there.

So I locked my keys in the car.. I called a friend to take me to where I'm staying to get my spare, but half way there realise that the house key is also in the boot of my car, and there is no spare outside the house.
We had to break into the house to get my spare car key so I could get back to the house.