Flavor text tends to fall into a few broad categories: the one-liner, the descriptive passage, the long quote, the real-world reference. Many subcategories exist as well, specializations such as the children's rhyme.
Given how important last words are in Western culture, it's no surprise that they crop up in Magic. Yet it's rather surprising how infrequently they show up compared to how memorable they are to flavor enthusiasts; only fourteen cards (as of this writing, of course) bear directly quoted last words in flavor text.
Fallen Empires was the first set to feature such a card, on a variant of Vodalian Mage. Like many last word flavor texts to follow, it is in the ironic vein (think the American Civil War general who took a bullet to the head right after saying "They couldn't hit an elephant at this distance!"), as the Merfolk in question most certainly can use magic.
The next set, Ice Age, had two further instances of "last words" flavor text. Rally is straightforward, a general's brave last words before death. And while Lhurgoyf's flavor text was meant to be serious, it achieved memetic status. Not only did it directly inspire "Ach! Hans, Run!" in Unhinged, it made "last words" flavor text a trope to be parodied on the same set's Bloodletter. It also inspired the designers of Time Spiral to make her a legendary creature.
In the following sets, use of the "last words" trope tailed off, seeing use mostly to riff on Goblins' lack of intelligence and propensity for getting themselves and others killed. Goblin Tinkerer and Viashino Cutthroat were printed within a couple of years of each other, while the flavor text on Bronze Bombshell of Ravnica block, if not spoken by a Goblin, certainly taps into the "too dumb to live" vein.
This is getting a little heavy, so here's the German version of Bronze Bombshell.
Ravnica block has another member of the "last words" quote club, Perilous Forays. While Perilous Forays is mildly humorous, the previous block, Kamigawa, has the ironic yet serious Kami of the Hunt. In the same vein, a few years later, Zendikar had the rather macabre Hideous End.
Recent sets have brought more frequent instances of last words in flavor text. Gorgon's Head borrows an incident from Ovid's version of the Perseus myth, in which a king challenges Perseus to prove he has slain the Medusa and gets turned to stone by the proof. Siege Behemoth takes the "military last words" theme and gives it a darkly comic turn. Twins of Maurer Estate marks the death of someone who's way too trusting to survive on Innistrad.
Of course, last words aren't just quoted directly in flavor text. Tenth Edition features two cards with evocative flavor texts about last words, though the exact words remain unknown.
And in a special case, a recent one at that, much is made about how a certain character gets no last words at all.
What's your favorite "last words" flavor text?