This is what happens when you leave Emily and Sabrina alone in a line, standing up, bored, and waiting during PE.
This is only one example of a variation of it.
Hermione=Sabrina Ron=Emily Ginny=Sabrina Harry=Emily
Hermione: Honestly Ron, will you ever stop eating? Your best friend is missing!
//Hermione and Ron get out wands
Ron:Crucio! (Doesnt work)
Hermione and Ron at literally same time: AVADA KEDAVRA
//both die //Ginny and Harry walk in, Draco walks up to them
Ginny: Where are Hermione and Ron?
//Many people step on H & Ron
//Draco points to floor
Harry: Honestly, Malfoy! What'd you do to them?
Draco: Nothing Potter, I promise. They killed each other.
Ginny: Honestly Draco, Stop lying!
Harry: Stop lying!!!!!!
Ginny: My poor brother is dead. Revive them Draco!!!!
Draco: Revivio! (Idk if this is a real spell)
//Ron and Hermione sit up
Harry: Hermione! Ron! What happened!
Hermione: Ron tried to kill me!
Ron: I am not Ron... I AM PETER PETIGREW!!!
//Peter fires random Avada Kedavra at some kid
Ginny: Go away Peter!
Peter: But... I am not Peter. I AM LORD VOLDEMORT!!!!!!!!!
Voldemort: AVADA KEDAVRA!!!!!!!!!
//casts spell everywhere
Harry: If that's Voldemort, then where's Ron??