In this Morning News article, Matthew Baldwin reveals the trade secrets of several professions:

"Mechanic

If you have to change a light bulb where the glass is broken, you can press a potato into the metal base to unscrew the remains of the bulb from the fixture.

Nurse

Patients will occasionally pretend to be unconscious. A surefire way to find them out is to pick up their hand, hold it above their face, and let go. If they smack themselves, they’re most likely unconscious; if not, they’re faking."

Read all the trade secrets here.