Soo... she doesn't like her big boobs? o.O
I mean--!!!... 'she doesn't find them normal' alrite... >.>;;;;
I suspect there's something wrong with the translation. Well, either that, or there's some kind of joke that I don't get at all.
I was under the impression that Blonde Classmate had realized that Mako says "normal" to mean "love" (in the scene where she gets a lightbulb over her head) and thus asked Mako about her "normal" for Sayaka to actually make her talk about love.
However, the question is "What parts of Sayaka are not normal?" (meaning: what parts you don't love) and the answer is "Her breasts, because they are so firm and soft." This doesn't make sense. Even less so if you consider Blondie's obvious shock and Sayaka's embarrassed reaction.
If the question was "What parts of Sayaka do you find the most normal?" (meaning: you love the most) everything would be much clearer.
It may be a bit confusing, but that's really how it is in the original.
A possible interpretation is that Shiki (the blonde, her name is mentioned in another one-shot) quickly realized that Mako would say "normal" as a denial, so she instead asked "What's not normal?" as in "What are you willing to admit that you like?".
(Or you can just think that what Mako meant is that Sayaka's boobs aren't normal, they are big).