What is the appropriate response to a seven-year-old boy who asks, while he has an erection: 'Mummy, what is my willy trying to tell me?' I have told him it's normal and it's just a sign that everything is working as it should be, but he keeps pressing me for an answer. I have distracted him for now, but need to be armed for the next time. (Surely seven is too young for The Talk?)