Yes there's a sign. The normal ammount of food they eat begins to make effect on them, giving them some sort of a belly and the face becomes broader. Also the nice-boy look in his eyes vanishes to become the elusive and hard stare of a man. He won't be able to contain himself at your curves (more intensely than a virgin boy) and will try at all costs to talk you to bed. If he is a gentleman, he won't be able to stare into your eyes for long. I know the signs. I have brothers and a never virgin ex husband.
