Poopies!

6 y/o (to the tune of "Go West" by the Pet Shop Boys):
  Poopies, fell out of the sky,
  Poopies, no need to ask why...

I'm unsure if I should be more concerned about the lyrics he has made up, or that he knows "Go West" by the Pet Shop Boys...

Superbutt!

5 y/o (while flying a doll around like Superman): Da-na-na-na-na Na-na-na-na Ttthbp! SUPER BUTT!!!

Truly, our house has the best super heroes... though they do seem to get into somewhat unusual situations:

5 y/o (now singing): Oh no! Your face is all tied up!

Then, from the downstairs bathroom, the voices of the 10 y/o and 8 y/o sing out in musical harmony:

10 y/o & 8 y/o (singing from the downstairs bathroom): Let me peeeeee! Let me poooooop!
5 y/o: They're crazy!

Favourites

In case there was any question as to which is the favourite parent:

S (5 y/o): Mammy, you'll miss me when I'm dead. But if Daddy was dead it would be great. We'd have lots of fun.