「杏子」is the compound for apricot (read as "anzu"), and is also the Kanji for Kyouko's name. Sayaka is switching from reading it as "Anzu" to "Kyouko" halfway through as a pet name.
HEY, Anko!Jeeze!Translation (You're angry?)She ate everything again!Today, I'm going to punish that good-for-nothing!