Why are you breaking the door in? Here's the key!
•Who broke in the door?
2. Fig. to use a new device until it runs well and smoothly; to wear shoes, perhaps a little at a time, until they feel comfortable. •I can't drive at high speed until I break this car in.
•I want to go out this weekend and break in the car.
•The new shoes hurt her feet because they were not yet broken in.