I'm gonna take a shot in the dark, in before translation, and guess this is a play on words to fool Lil Chen to think she's getting a treat. But in the end, the cake was indeed a lie.
I get it. Chen needed to go to the dentist, cant have sweets, Yukari promised sweets to Chen knowing she wont be able to eat them and so she would be good at the dentist as well. Now Chens waiting and waiting... and waiting, Yukari is getting her punishment lol.
Che~n, Che~n, Che~nnagoAs expected, they don't realize...F- Forgive me...DentistChen~ and Nazu~ ♪They get along so well
They don't fight~♪
The Japanese opening song of Tom and Jerry. See also http://www.youtube.com/watch?v=gs-LUmDhZpw.Nazu~, Nazu~, Nazu~chu~ "Chu" refers to both the sound mice make and kisses.
ケーキ
歌
Chen, you've been a good girl all day today, so I will buy you sweets!Gonnng"Failing" signal in NHK Nodo Jiman.
HugBlush