I've had this sitting on my hard drive for the last two months, and I keep forgetting to upload it until I play and hear this. Anyway, I extracted and spliced enough of Cave's dialog to create this: he says the words "pills" and "here" during the course of the game, but not in such a way that playing them together sounds any good. So, after splicing several consonants in and out, we get this.
Listening carefully, you can hear calm Cave, angry Cave, and stuttering/slurring Pillllzzzz Cave, simultaneously.
Transcript: (_GET MAD!_) I'm C-C-Cave Johnson, (_Do you know who I am?!_) do not touch anything, (_BURN YOUR HOUSE DOWN_) I own the place- (_WITH THE LEMONS!_) -can't _believe_ I'm thanking these people....
Also, this works in both L4D1 and 2, and the DL also contains the .wav file in case you'd rather not extract it from the .vpk file.