There were two:
Does Jesus make people do stuff?
What does “crucified” mean?
My answer to the first question (after a long pause): “Jesus can make people do stuff. Jesus can do anything he wants to. But he usually doesn’t make people do stuff. He lets them decide.” Some will disagree with this. But I think it has pretty good Scriptural warrant. I’m sure this question will come up again. And I thought the sex question was hard!
The second question I answered as specifically and succinctly as I could. I actually got a little teary-eyed as I described crucifixion to him. His response to my answer was appropriate, I thought: “Why did they do that?”