Locked car

Finding a woman sobbing that she had locked her keys in her car, a passing soldier assures her            that he can help.
She looks on amazed as he removes his trousers, rolls them into a tight  all and rubs them against the car door.
Magically it opens.
"That's  so clever," the woman gasps. "How did you do it?"
 "Easy," replies the man. "These are my khakis".