Dumbledore and Snape:

Dumbledore: Severus. Kill me.

Snape: What? Why?

Dumbledore: You can't let Draco kill me now, can you?

Snape: Why would anyone kill you?

Dumbledore: Don't act clueless, Severus. We both know that Draco was assigned to kill me. We know he won't follow through.

Snape: Yes, he's only sixteen, that's expected.

Dumbledore: Also, I have an infection that will kill me within a year, so I need you to do this.

Snape: Albus? Why do you want me to kill you? I can't kill my boss, that's strange!

Dumbledore: You can if they ask you to.

Snape: I guess so. Narcissa made me take the unbreakable vow with her to protect Draco from all harm, so I guess I'm going to have to kill my boss.

Dumbledore: Don't be alarmed, Severus, you saw this coming. Also, Harry and I will hunt for horcruxes.

Snape: You're using him as bait! What are you thinking?!

Dumbledore: Severus. Calm down. I'll keep him safe.

Snape: If you say so.

Dumbledore: Kill me at the astronomy tower. Tonight.

Snape: Consider it a deal. I'm only doing this to protect Draco.

Dumbledore: I know. We can't let a teenager go to Azkaban.

Snape: Consider it done.