Buy one, I guess. Maybe one of the stores on the island sells them. I don't know how to get one the right size, though. I guess you measure somehow.

[He continues to fondle Roxas under the pretense of measuring cup size, except cup size is an arcane mystery no man shall ever master and he's starting to feel like a creep, so he reluctantly lets him go.]

I don't really know how it works. You'd probably have to ask a girl.