The first and foremost ques (for food adulteration) is:
"Was the biscuit your school gave me to eat poisoned?"
Answer: (politely)
"Of course not"
Question:
"Was there something else in it?"
Answer: (Innocently)
"Nothing much, Sir. Just a few pills of horse laxative"
Question: "Are the toilets in ur school clean?"
Answer: (Apologetically)
"Don't know, Sir. Depends on the amount of laxative given to the other external examiners"
PS
NOT TO BE TAKEN SERIOUSLY