Why Can't You Say Good Night?

Parting words, coming after drugging someone but before the victim hits the ground. May take the form of a Preemptive Apology. A kind of Pre-Mortem One-Liner without the actual, y'know, death. The last words from the guy they drugged are Parting From Consciousness Words.

Trope name comes from Tony Basil's "Mickey".

Film
"Hudson Hawk: Hey, this doesn't taste like cappuccino.
 * Hudson Hawk.

Anna: Oh. I guess I put too much ethyl chloride in it.

Hudson Hawk: [collapses]"

"Casanova Frankenstein: "It's a chloroform-deploying portable enticement snare."
 * Mystery Men: Right after Captain Amazing asks whether what he just picked up is not evidence, it shoots out a cloud of pink smoke:

Captain Amazing: "... - Ah, dang!""

"Irene: I told you to let it breathe."
 * Sherlock Holmes

Live Action TV
"Ethan: "You... probably shouldn't have drank that so fast...""
 * Dexter: explains how ashamed he was at accidentally leaving one piece of evidence as the Ice Truck Killer.
 * And, of course, Dexter himself often whispers a one-liner to his victims right after he slips them the needle.
 * Played with on Lost. was handed what was told to her to be a glass full of tranquilizers.

"Mohinder: "I already have you, Mr. Sylar.""
 * Heroes: Mohinder to Sylar

"The Baby-Eating Bishop of Bath and Wells: Drugged! By God!
 * Blackadder:

Blackadder: By Baldrick, actually, but the effect is much the same."

Manga and Anime
": Good night,."
 * Tiger and Bunny

Video Games
""Nothing personal. Can't risk you going berserk and getting Lisa killed.""
 * Mona Sax, right after drugging Max Payne:

Web Comics
" : T-tut mir leid. ("I'm sorry.")"
 * After Jordi is drugged in Cuanta Vida:

"Lucrezia: Not poison, silly. I'm one of the good guys now, remember?"
 * In Girl Genius:

Western Animation
""You'd be surprised at the amount of chemicals the average cigarette contains.""
 * The Venture Brothers:

""Logan, buddy! It's me, Deadpool! I shot you.""
 * After a certain mercenary tranquilizes Wolverine in Hulk Vs Wolverine...

""Tell me, Batman... What question can you never answer "yes" to? Are you asleep?""
 * In The Batman, after the Riddler sprays Batman with knockout gas: