Accidentally threw away all your underwear

You wake up in the morning and after a shower you find that nothing is left of your usual underpants. You go to the closet. Everything is lost!

Oh sorry honey - your mom says. - I saw that your clothes are quite old, and I decided to throw them away. And I did not think that you would have nothing to walk. But you can ask your sister for panties.

Out of desperation, you are forced to ask your sister to give you something from her personal underwear. She quite willingly agrees and after a while you are already standing in nice black panties, practically not covering your penis and testicles.