Pillowcase Swap Gone Wrong

I did a pillowcase swap with my friend Lily. We were supposed to take each other's dirty pillowcases and put them in our own beds for the night. But I forgot to wash mine first, so when she came over the next day, her nose scrunched up and she said it smelled really bad. She had cleaned hers before giving it to me, but I was too lazy to do the same. Now she won't let me forget about my stinky pillowcase stunt.