Help identifying a pop culture reference

[tahnan]

So I was leaving the room after tucking my wife into bed last night, and as I reached the door and was about to turn the light off, she called out, "Hey! You forgot to turn the light off." I answered, "Hey, I'm still right here..." And we both paused and, more or less at the same time, asked, "What's that from?"

If you don't know the exact quote, Googling is useless, but someone out there must know. Person A starts to walk off, persons B and C say "Wow, he's annoying", and from just off-screen Person A says "Still right here...haven't left the room yet..." It's from something, we're sure of it. But what?