Don't think of any questions that are used to "test" a psychic. I tried this, it blocked them, and I proved to myself exactly what I wanted to hear - that their abilities are BS.
However, a short time later I tried something different. I chose to assume that a psychic was legit and asked myself "IF I already believed this psychic was for real, and I've got the opportunity now to ask them person ANYTHING, essentially to have an open session with my spirit/soul, what are the questions which would help me most right now in life?"
That created a totally different set of questions. When I got the reading, the questions gave me REALLY clear answers and at the same time proved to me that the psychic abilities were real, even though I wasn't going for that anymore.
Get your ego out of the way. Imagine you're writing a movie in which your character goes to see a psychic. This is a fantasy movie in which psychic abilities exist and everyone already accepts that. What would your character ask the psychic that he goes to see?
When you go see a laywer, do you ask them questions to test if they know law?
When you go see an accountant, do you ask them questions to test if they know accounting?
When you go to see a doctor, do you ask them questions to test if they went to Medical School?
No, you just ask for an answer to whatever is troubling you. Do the same with the psychic and you may be pleasantly surprised. You may also want to meditate the night before and tell your spirit/subconscious mind something along the lines of "Tomorrow I'm going to see a psychic. I am ready to accept that such abilities exist and are possible. I would like you use this psychic's abilities to communicate the answers to these questions:"
Hope this helps.