Furious GF's breast expansion

You’ve said before that you kind of wish your girlfriend’s breasts were bigger, and she’s always rolled her eyes at you. Sure, it’d be nice if they were, but it seems like too much hassle and expense to get implants, she shrugs. One of your workmates claims he has a solution, like a potion. It sounds dubious, but he reckons that his wife’s tits are enormous now. Like two beachballs, he confides, eyes shining. You figure, what the hell. It doesn’t hurt to give it a go. Your girlfriend is less convinced. First, she tells you the whole idea is the stupidest thing she’s ever heard, then when they DO start growing she’s furious. This was YOUR idea, she hisses. When are they going to stop getting bigger, she asks