Well, to be fair, they're going from the assumption that she doesn't know what will make her come, and she herself doesn't care that much, as Momoko noted.
Either way, I find Emi's deconstruction of the "bigger is always better" concept quite entertaining.
Also, I almost had Taro saying he thought he had a "no-nut nakama" just for alliterative purposes (either way I actually pulled out a thesaurus looking for a good word).