Old Quote

Hey, Carly's here. I was watching a VERY old Doctor Who episode, with Sylvester McCoy, the 7th Doctor. I was reading a book and only half watching it, and his companion (haven't the faintest who it was) and him said the most AMAZING quote in the show. I dodn't have it comepletly right. But exact same concept.
Doctor: Are you a bad child?
Companion: No! I always do as I am told!
Doctor: Good. Go blow up that vehicle.

Loved it, but wish I knew 3 things about it:
1. What episode it was
2. Who his companion was
3. What the EXACT quote was.

If you could find this out for me, it would be amazing!
I remember one thing-there were cybermen, and a thing with a weird name, like desire or something. Ugh.

PLEASE help me find this quote! See you later

xoxo Carly