The deal of having to provide a thousand pussy lickings is diabolical. I can see him serving the volleyball team right after a victorious game, while they're all still sweaty and celebrating, examining his chastity, teasing him with their bodies, and mocking him for getting into such a fix.
I'm sure that as his chastity goes on and on, he'll say 'yes' to anything that helps bring that thousand count down. And once the girls realize that, well, they'll know they can demand practically anything in return for allowing him the 'privilege' of licking them to orgasm. He might find himself doing some humiliating things!