It has multiple defintitions,
Killed, for instance, but also can
mean that you're
totally f*** up on acid.
To shout "GET TOASTED!" at someone, for instance, means that you think that person should eat acid and kill their egos.
GET TOASTED!! (Eat acid and die!)
Sorry I'm not going out tonight, I'm totally toasted in my room right
now, petting my
fish.
I can't drive right now I'm way too TOASTED
man. I'm TOAST!