He comes around these girls who absolutely adore him and his timid, dorky antics. He says nice things and tries to be gentlemanly, all while failing to hide how outrageously interested he is in them. He stares at them and blushes when they catch him... and he also has a giant, nanotech dick. But he's too shy, and girls are unable to make any successful passes at him beyond some hugs, cuddles, or gentle petting.
He's not stupid, either. He knows he drives Milkette nuts and yet he keeps on doing it! So imagine her delight when he shows even the slightest interest in getting to first base. Milkette loves first base. In the metaphor, she may as well be the first baseman, there at the ready for any cute boy who wants to slide on in. With the right person, Milkette will draw the most sexual of pleasures from exploring every inch of their mouth with her tongue. It can be a rather intense exchange, but the beauty of kisses remains that they may be as tender or as hardcore as the situation calls for. They're also perfect for escalation and deescalation of any intimate exchange. It's like having a controller, but the joystick is a pink, warm muscle inside your face.
So, she surprises Jon while they're alone at her place watching movies. And that surprise is going to continue for some time - she has a lot of sexual tension to make up for. Sure, she may not find Jon's 100% all-beef thermometer stuffed into her hot pocket, but it's a face-sucking in the right direction.
Plus, with enough tongue-swirling practice with Milkette, he'll be fit to dine at the Y in no time.