Gamzee's eyes widened slightly at the feeling of the human's half-stock against him through the layers. He wasn't sure what it was, but it was certainly no bulge. He knew, through hearsay and Terezi's accounts, that the human equivalent was always out and stationary for the most part, but it felt more like a thin arm between his legs rather than any motherfucking bulge. He ground against it again with a more serious look on his face, just to size it up, to feel it against him without reaching down between them to use his hands.

"Reeeal interestin'," he purred as he brought his lips across Dave's, not to kiss, but to tease. "Shame I be hearin' you ain't got a nook. Coulda fucked that real good." The tone to his voice took a darker edge as he talked dirty, but he kept himself at bay. This was straight up just for exploratory purposes.