I got something ridiculously straight forward.
There were 5 cards on the table, and they had various numbers and letters on. They said "Cards with vowels on have odd numbers on the back" Which card would you need to turn over to check this assumption? The answer was obvious, it was the card with vowel on, I think it was an A or something. ANyway, yes, I dithered, I thought it was a trick, I sat there saying "Ah, but do all cards with odd numbers on have vowels on the back?" etc etc, but it really was the straightforward answer he was looking for. A lesson in not overthinking I suppose.