The Red Hand of Sauromon
When your partner is menstruating and you slide your hand across the blood to cover your entire hand. Once covered in blood, you stamp your paw print on her mug and exclaim, The Red Hand of Sauromon!
"Okay so here I am wrecking Éowyn's guts when I notice she is on her period so I slapped her with the Red Hand of Sauromon."