When you have sex with a woman, but have no intention of dating her at all. The actual guilt comes in when you encounter this random piece of ass much later, and while thinking of the sex, can;t think of anything to say. You walk away with a boner and a feeling in your stomach that your a horrible person.
"Damn dude, remember Danielle? I ran into her the other day out in front of Trader Joes, and she just kept going on and on, but i couldn;t get her to STFU. It was a serious moment of penis guilt.
What did you do?
Went inside, bought some malomars and went on with my day."