When you discover a wardrobe malfunction in daily life, it really gets your blood pumping, doesn't it? Yes, erotic opportunities directly stimulate male instincts. Even a brief glimpse can be incredibly exciting, but if someone intentionally flaunts it under the bright sunlight... of course, an erection is inevitable, and pre-ejaculate=penis fluid=cum will keep flowing. What would a wife think seeing such an erect crotch oozing with erotic fluids?
