Sayaka's bubble in panel 3 literally translates to "Reverse! Hand reverse!", which I imagine is just slang for "Good! Very good!", but eh. A cursory Googling revealed nothing useful.
Yes!Uh,If this got out, it'd cause me a lot of trouble.Sorry, but...I learned Miki-san's secret...I...And we made a promise, just the two of us....could you keep what happened today a secret?...Please....Oh, well.That's why...I'm too excited to sleep...Right hand!Give me your right hand!