Offer him an alternative

"Wait!" you say.

Junior hesitates for a second. He looks angry, clearly still mulling over the (totally justified) curses you threw his way only a few seconds ago. But his curiosity gets the better of him, and he slowly descends to the bottom of the stairs again, waiting for you to continue.

"Come here," you hiss, pointing at the ground and stomping your foot.

He does as you say, that old creepy smile growing on his face yet again. "So you're going to do it?" he says.

"No," you say. "But!" You make sure to add the 'but' before he can turn away to leave again. "But, if it's a blowjob you want, I might be able to help you out anyway."

"Really?" he says, perking up. "What do you mean?"

"I'm not going to give you a blowjob. But I can get someone else to give you a blowjob."

The owner's son looks conflicted. Clearly he was excited to get head from you, but he might be willing to settle for getting head from someone. After all, it's not like he's losing anything in this bargain.

"Okay," he says. "But this had better be good. Who did you have in mind?"