A secret door slides open, revealing a hard, pulsing cock. An invisible tongue flicks out, licking the tip, tasting the pre-cum. The mouth envelops the shaft, sucking hard, the cheeks hollowing out. The man grunts, his hips thrusting forward, fucking the invisible mouth. The stranger's tongue swirls around the head, teasing the sensitive spot, bringing him to a shuddering climax, his cock pulsing as he spills his load into the welcoming, anonymous mouth.