You know, they could troll her back with Magical Girl off of the Jet Set Radio OST (because bad things happen when she becomes one) or Cruel Angel's Thesis (because she's Shinji with a vagina).
Do [Forward to the Invasion] here related to any of them?
Take a look at the lyrics Kyouko is singing. 4th panel.
Forward to the Invasion!I'll Kill Your Ex-BoyfriendUpcoming songsMagical Girls in Karaoke ParlourHere, Madoka, we brought drinks.Thank you, Sayaka-chan!Oh, while I was waiting, I've ordered songs for everyone.Huuh? Hey, wai-... what are you doing!?It's café latte!Going alone is lonely, so why don't we go together like this ~ika?
Lyrics from Ikamusume OP.