"You stock Oxycontin on the rigs right?"
"Does your life insurance policy cover suicide? Yes? Does that stairwell have roof access?""While your at it, could you describe your controlled substance security procedures in detail?"
"While your at it, could you describe your controlled substance security procedures in detail?"
Along with any codes and procedures involved with accessing said substances (with illustrations where necessary)
"Random drug testing is not part of the union contract right?"
"How detailed are your background checks?"
"How do you feel about Dr. Kevorkian's ideas on end-of-life care?"
Seriously, pay, orientation process, protocols, career ladder, QA/QI, equipment and schedule are all fair game for me in an interview.
You should also not wear a khaki military uniform, mirrored sunglasses, speak only in Arabic and refuse to answer questions.