Deathly Hallows???

I'm not hyper yet. I should be, I really should be. I can't even figure out how to think about what it might mean yet, but there's this sense that once I get started, I'm going to be more hyper than Juno and Tasha combined. I'm...I think I'll be bouncing in a moment or two, and my brain is as focused as it can get. *bouncebouncebounce*
Why "deathly"? What does it mean?