Snape killed Dumbledore 

An expression inspired by the 2005 internet fad around the Harry Potter and the Half-Blood prince in which the character Snape kills Dumbledore.

"Snape killed Dumbledore" is closest in meaning to shit happens or I don't give a shit and is is used as an unsympathetic comeback, similar to Jesus wept.

Guy 1: "Balls. I just failed another Calc test. Another, and I'll fail the class."
Guy 2: "Snape killed Dumbledore, you know? You always complain about failing classes, why don't you study for once?"

Snape killed Dumbledore by Ben Dover! May 26, 2006

Snape killer 

A person who kills another person from the opposing side, to gain the trust of their master, just to bring them down.
For example, Severus Snape killing Albus Dumbledore in the Harry Potter series to gain trust of Voldemort

Snape is a snape killer, he killed dumbledore just because of that!

Snape killer by JariPinda March 16, 2017

Snapekilled 

Killing someone you love to prove your loyalty to someone your spying on

Kylo ren might have snapekilled han solo

Snapekilled by Epicface999 September 11, 2016