Diaper Change

Millie loves The Wonder Pets. The main characters are a guinea pig named Linnie, a duckling named Ming Ming and a turtle named Tuck. Each episode is a mini musical with some repeated refrains so you can sing a long. The duckling often sings at the climax of the show "This... is... sewious..."

Just now during a particularly pungent diaper change:

Daddy: Whew!
Millie: This... is... sewious...

This... is... hysterical.