He'd been out having a dram (work do) and made his weary way home with a good drink on board, in the dark.
He got to the back door and thought well I can't find my keys, and I can't get in. What am I going to do now?
So he decided to go in the dog flap at the bottom of the door (as you do).
He couldn't fit through the flap though, so he took off his jacket and laid it on the ground, and tried again.
Finally after a right old struggle, he managed to get himself squeezed through the dog flap and landed panting on the kitchen floor.
He pulled himself together, gave his drunken head a shake, and remembered that his jacket was still lying outside on the garden path.
So he thought he'd better get the back door open to get out & pick up his jacket.
Although he'd a good skinful, he did manage to look at the back door closely, and noticed now that he was inside that the key was in the lock.
He had a funny thought, oho! and without turning the key, he tried the back door ...
And discovered it had been open the whole time!
(true story btw)
- Ken D