I've got the balls and cum. You work for a company that buys semen. To ensure both production quality and amount, men hired are not allowed to cum for a week before a deposit.
Perhaps you are a researcher trying to find out which techniques or stimulation or drugs can increase frequency and loads.
Perhaps you make home visits with a portable machine to do the milking.
Perhaps you just enjoy teasing the men that come in. Enjoying having them under your control and shooting on command.
Whatever you like about this prompt, message me and we'll work out some details. We can play by private message or Discord.