L-Slides are neat, simple tools that can let you open a closed door. Locked out? L-slide!
Step 1: Create your 'Slide
The method of choice is to scrounge up some brick-strap, which usually floats around construction places.
Use pliers (to bend the metal back and forth along a line until it shears) or bolt cutters, to cut the length you want.
Then, bend the brick-strap to a ninety degree angle, creating an "L" with one longer side and one shorter side.
Use any method available to you to pound the angle flat.