He ties it down

Andrew grabbed a roll of string, and pulled out a decent length of string. He then started wrapping the string around his slaves ballsack, making it jut out, then he wrapped it around its shaftat the base and just below the tip. Then the string was wrapped around his slaves waist, holding its dick against its stomach.
"There, much better." Andrew smiled, stroking his slaves bound cock, now straining against the string.

His **** groaned when he stroked the tip, then moved down its shaft to its balls. He cupped them gently. "So big, I bet they´re full of cum already. But..." He squeezed them, hard, making his slaves squeal through the big ballgag. "You´re gonna have to earn your every release from now on, understand?" His **** nodded, relaxing as Andrews hand moved away from his balls and moved up to his nipples. "Since you've read my mind, you know what comes next, don´t you?" His **** nodded, a nervous look in its eyes.