The cool, hard cock pressing against the soft, wet mouth on the other side of the wall is a thrill like no other. The sucker swirls their tongue around the head, tasting the salty pre-cum, before taking it all in, inch by inch. They can hear the stranger's ragged breaths, feel their body tense as they approach climax, and just as they're about to explode, the cock disappears, leaving them craving more, eager for the next anonymous encounter.