I assume this comic was written before Ami and Mami show up in Idolmaster: Xenoglossia.

For more on the "cabbage", see: http://en.wikipedia.org/wiki/Yoake_Mae_yori_Ruri_Iro_na

(Also, I have no idea what "tokachitzukushi" means)

(Also, I have no idea what "tokachitzukushi" means)

More than likely, referencing the way the twins mispronounce lyrics, most reputably in "Agent Yoru no Yuko"