Good point, but I feel like they could probably just translate that scene without having the innuendo (like the direct translation for “beach off” probably doesn’t sound anything like the translation of “beat off”, so it would become more of a whimsical non sequitur directly translated).
I think there’s a fair amount in this movie that doesn’t really translate well outside American/Western culture anyway. For me, that scene was funny because it’s repeating a pun that points to the Ken characters’ innocence when in the real world, they’d be mocked mercilessly by some people. And it forces the audience to think about their own reactions when insecure straight men sometimes follow sentences like that jokingly with, “no homo,” to point out that, despite unintentionally saying something that sounded kind of gay, they are not in fact gay. At any rate, I don’t see this scene as an endorsement of homosexuality, but rather a commentary on society’s fixation on hypermasculine language.