My son is now almost 5 and he still likes them. Well, at least he did this past summer. I have managed to keep them away since then, in part because I find them disturbing and in part because he doesn't watch TV all that much. If he was watching TV and the Boohbahs happened to come on, he did stare at them memorized for a while. He didn't start bouncing though, he just sort of sat there, slumping with drool slowly coming out of his mouth. About what you expected, no doubt.