a short form of, or rather, more polite way in saying mother-fucking. Derived from effing which means fucking by adding a 'M' in front of the word. Hence 'M-effing'

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.

When one human consumes methamphetamine and starts flailing. Or acting like an asshole. Usually done out of public site.