Is it really possible to open a locked door with a credit card?

yes, but make sure you don't use one you want to keep. or don't. i don't care.

if you open a door and look at it from above it's shaped like half of the letter D i think it only works when you press the curved part back into the lock.

On the older doorknobs (look in the crack between wall and door, the bolt has one layer), it will work, just push the SOB in.

On the newer ones (The bolt has a big knob and a skinny one in front of it), it won't work as easy. If the door opens out toward you, then smash it in a bit, (so the little bolt will enter) then try it. Some, but not all doors have that much give.

Preps suck.