I'll be in the garage is a reference to the show "Rick and Morty where rick and his lover call it off. He gets home and tells his family how life is meaningless and says I'll be in the garage, where he has a attempt of suicide.

n. The birth name of somebody who has changed their name. Most commonly attributed to trans people, but can be attributed to any person who has changed their name. (sometimes written as two words: dead name)

v. 1. To call somebody by their deadname.
v. 2. To out somebody's deadname to the public.

Slang for planning to commit suicide