Common Sense Modification (CSM)

It's the morning commute, and the train is nearly full, save for two open seats. A short, redheaded woman starts to walk towards one of the seats, but before she can sit down, two women in matching white blouses rush past her and take the seats for themselves. Instead of looking flustered or annoyed, the redhead just smiles. She turns to you, You, and gives a cheeky wink. Without warning, she reaches out to touch your arm, causing a small black mark to appear on the back of your hand. She whispers in your ear: 'Check this out!'