Reference to film star Greta Garbo, evoking a quiet, mysterious, private, calm, serene, poised disposition. Not needing to justify yourself; allowing the other person to imagine whatever they like while you keep your cool.
"Tranquility is the greatest manifestation of power."
Verb.
When you're just so unbelievably pissed with something that normal swear words won't satisfy you, like viruses on your computer. (From the Norton commercial)
Dude#1: Man, you were too lazy to listen to all those damn Norton pop-ups and now your computercrashed.
Dude#2: Are you Garblesnorting me?!