The killing curse defined the entire franchise of Harry Potter. It was the curse that marked the beginning of Harry Potter's story - when it was cast upon him at Godric's Hollow - and the end of the franchise, when it backfired and finally killed Lord Voldemort.
Harry was the first person to survive the deathly effects of "Avada Kedavra", but many others were not so fortunate. In spite of its unforgivable use, Potterheads have found the funny side of the curse and have made hilarious memes about it.
Avada Kedavra
Avada Kedavra's etymology is based on the Aramaic אַבַדָא כְּדַברָא, which means "let the thing be destroyed". Given its original language, it has a very specific pronunciation that differs from "Abracadabra".
Of course, Potterheads know this very well, but also Hermione Granger. Although she was never close enough to Voldemort or Tom Riddle to correct his mispronunciation when casting his favorite spell, it is not hard to imagine that a young Hermione would have done it.
Spell Discovery
The killing curse is one of Harry Potter's most dangerous spells. It immediately kills whoever the spell is cast upon, except for Harry Potter, of course. As the meme points out, the person who created the spell must have had a tragic, yet hilarious, discovery of the curse.
It is not known who created the curse. It is only known that it first appeared in the Middle Ages and that it was used by dark wizards to slay their opponents. It is probable that the wizard who created the spell did it intentionally, however, it is much funnier to imagine it being created by accident.
Popular Curse
Since it was first invented, the Wizarding World soon considered it one of the spells that should be illegal, and eventually prohibited its use. However, its illegal nature made it more intriguing for most, including Harry Potter fans, and it is safe to say it's one of the most popular curses.
Its phonetic similarity to "Abracadabra" and its deathly means made it easy to remember. Consequently, many Potterheads can hear Voldemort's phrasing of the curse when they see the picture shown in the meme. Ralph Fiennes' powerful and iconic pronunciation is hard to forget.
Short Harry Potter
If Hermione Granger had cast the killing curse instead of "Oculus Reparo" the Wizarding World and the Harry Potter franchise would have been very different. Nonetheless, it is hilarious to imagine that Harry Potter and the Sorcerer's Stone could have ended at that moment.
Harry Potter's inclination to survive the killing curse may have saved him from a moment like that against the brightest wizard of her age. Fortunately, none of this actually happened, and fans got the other six books and seven movies of the franchise.
Killer Hermione
Certainly, "Avada Kedavra" is one of Harry Potter's best spells, and fans have a blast imagining all sorts of situations where the curse is used. They seem especially amused by recreating scenes where Hermione uses any other spell, and they change it to the unforgivable curse.
The trend is undeniably funny and it is especially hilarious to imagine Hermione using it upon Cormac Mclaggen in the Quidditch Tryouts in Harry Potter and the Half-Blood Prince. However, her love for Ron Weasly would never drive her to kill anybody.
Hurts
Dogs don't have the ability to cast the killing curse, however, it is hilarious to picture them doing so, especially in this meme template. As it points out, a bite would definitely be way better than receiving the killing curse.
"Avada Kedavra" may be one of the fan-favorite spells from the Harry Potter universe, however, it is quite unlikely a dog would use it upon any human. They are really kind-hearted animals, and only humans have the desire of killing their own for the sake of it.
Deathlier Than Petrificus Totalus
It is a mystery why fans rejoice in making Hermione kill other characters in the franchise in memes, but it is definitely undeniable that of the three individuals of the Golden Trio, she would be the most equipped one to use it.
She probably knew about the spell since she was very young, while most students of her age were oblivious to the fact that the curse existed. At the moment depicted in the meme, she actually used "Petrificus Totalus" but it would have been way more dramatic if she would have killed Neville for getting in her way.
Used By Voldemort To Kill His Family
The killing curse was Voldemort's signature spell and he started using it when he was very young. He hated his father, Tom Riddle Senior, and his entire family. As soon as he had the power and stomach to do it, he slaughtered his own family.
Nobody justifies his murders, however, his upbringing could easily explain why he became such a bloodthirsty and apathetic individual. Tom Riddle senior was not even close to being as friendly and attentive of his son as the meme shows, nevertheless it is hilarious.
Harry Potter Survived It
Harry Potter was the first person ever to survive the killing curse and because of it, he became an instant celebrity. The moment the curse was cast upon him was way more dramatic and tragic than the meme depicts, nevertheless, it sums it up perfectly.
Baby Harry Potter was pretty much just hanging with his beloved mother Lily, when Voldemort barged in, tried to get Evans out of the way, and tried to kill the boy. As the meme hilariously depicts, in summary, Potter was there, seeing Voldemort, he then saw a green light reach his forehead, closed his eyes, opened them, and had a brand-new scar.
Gets All The Attention
The killing curse gets all the attention, but in truth, it is the least bad one of the three unforgivable curses. Potterheads do not forget that it was with the "Crucio" curse that Neville's Longbottom's parents suffered a destiny worse than death and became mere shells of who they once were.
Imperio has a similar effect, people don't stop living perse, but they lose the capability of their mind, and become someone else, which for many, is worse than immediate death. Like the meme hilariously depicts, in spite of being just as bad, or even worse, Crucio and Imperio didn't get any of the attention they deserved and were cast aside like a kitty that lives with a puppy in the same household.