The Powerpuff Girls, Season 1

Narrator:
Aww, it's the first day of school, but what's this, Pokey Oaks Kindergarten is closed?

Blossom:
What happened?

Buttercup:
Don't you remember?

[Flashback begins with Bubbles, in her original 1998 counterpart's design, presenting to the students at Pokey Oaks Kindergarten]

Bubbles:
For my spring break, a fought a giant space crab on a radioactive comet with my sisters. I found this goo after he exploded. [She accidentally threw the bottle of goo] Oops.

[The bottle of goo mutates Pee-Wee the class hamster and he starts to grow huge as the students ran away; End of flashback]

Bubbles:
Oh, yeah. [waves] Hi, Pee-Wee!

[Pee-Wee turns to her and grunts out a barely intelligible "Hi Bubbles!"]