Not 11+ but a question posed in the entrance exam for an Oxford college. "Is this a question?" The best answer, apparently, was "If it is, then this is an answer".
I not only did (and passed) 11+ in my local primary school, but also did an entire day of entrance exams and interviews for my secondary (girls' public) school. Years later, when it was ingrained deep in my soul that my older sister was the favoured, valued, bright (and beautiful) one and I was the family clown, my mother casually mentioned that the head of the school had said to her, "We were impressed when your older daughter did the entrance examination, but your younger girl's marks were exceptional." Thanks Mum, that could have made all the difference.
Survived it though.