My favorite catchphrase of his is "What's goin' on here?!" I was delighted whenever it was repeated and it got funnier every time! They even had Henry Aldrich say it!

I also like "Ohhhh...razor!" or whatever object he forgot and "Ooooh, what she said!" Dennis' lines always got a big laugh, even from the cast!
What's your favorite Dennis catchphrase or moment?
