Those should be the first words out of your mouth.....
Arrive at a first blind date - "I can't have children!"
See someone across a crowded theatre.....they look back with a rye smile - you say, "Hey you"...."yea you" (pointing at her) - " I can't have children!"
See a girl you might be interested in, ......go buy flowers and knock on her door,.....one of her parents answer, you say "Is Julliette there?" She comes to the door, - "Hi! You don't know me but my name is Bill, and I can't have children!"
That would be the "christian" thing to do..............