In the dimly lit room, a lone figure, his heart pounding with anticipation, applies lube to his erect cock. With a steady hand, he inserts the tip of a metal sound, his breath hitching as it slides in, stretching his urethra. He pushes it deeper, feeling every ridge and curve, a symphony of sensations coursing through him. His moans fill the room as he explores his limits, the sound disappearing into his cock, his body trembling with taboo pleasure.