when your at a friends, a relatives, or even your girlfriends and they have to leave the house for some reason and your all alone and you rub one out and when they get back they dont know (sometimes they have a suspicion and look for clues) because u dont leave a stain, tissue and not even the internet history or even a boner when they meet you unexpectly
grannys tried to catch me slippin with her fast hd laptop and her nice guest bedroom with a kleenex box conviently placed on the nightstand but little does she know ima no trace fapper