when you eat out a chick who is on her period, knowingly or unknowingly
my roommate got wasted on his b-day and comes out of his room with light blue boxer shorts with blood crusted around the dickhole of the garment. I asked him, "dude, is your dick bleeding?" He relpies, "No that chick I fucked must have been on her period. Oh no, I must have eaten her out", with a horrish face.